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I expect to be downvoted for saying this, as some people are really precious about the idea of 4-day work week, but I really struggle to understand how working

I expect to be downvoted for saying this, as some people are really precious about the idea of 4-day work week, but I really struggle to understand how working fewer hours will not result in loss of productivity. If for some reason it is true that working 4 days a week results in the same amount of productivity, then why are 3 days a week not even more productive? Or 2? This is obviously reductio ad absurdum but that would mean that people who work 0 hours are the most productive ones. I know that there is the argument about "if I have fewer hours they will be more focused", but that to me sounds like it's entirely wishful thinking and in a few years will be having the same amount of wasted hours in those days too, as people start thinking of Thursday as the new Friday. I assume there is some sort of middle ground between working too much and working too little. Are there any actual evidence that that optimum middle ground is 4 days and not 3, or 5? I would find the whole idea much more palatable if it wasn't sold by claiming something likely isn't true (people working fewer hours do more work), and instead someone was honest and admitted that this is a political project. What I find much more interesting is switching from a 7 day week to something else entirely, for example working on: Monday, Tuesday, Wednesday is free, Thursday, Friday, Saturday, Sunday is free. I can see how that might result in people being more productive, as they still work the same amount of hours, but they don't get as exhausted as before.

vorpalhex 4y ago
We need to do experiments and gather data to test hypothesis. This is one of those experiments.
adamckay 4y ago
The no loss of productivity can be a combination of multiple things: a) There is loss in productivity but it isn't (or can't be) properly measured or does not make an impact on the business, e.g. a help desk responds to customers with 1 business day rather than 4 business hours. b) People are more motivated (including it being a novelty) so employees are eager to work harder in their reduced hours to ensure they can continue a 4-day working week. If this becomes the norm after a while you may see this slack off. c) Lots of people are doing busy-work or "bullshit tasks" which do not actually affect business productivity or are simply just looking busy and procrastinating, e.g. office workers browsing Twitter, Reddit or HN for a short time every couple of hours which is eliminated. It highlights saying "don't confuse activity with achievement/productivity".
lolinder 4y ago
Most systems don't have a nice, clean, linear relationship. You did a reductio ad absurdum in one direction, let's do it in the other: if hours worked directly translates to productivity, then we should be able to add more hours and continually get more productivity. Why not add Saturdays and Sundays back in? Then we can go to 10 hour workdays. Maybe 12 hours? Even aside from the humanitarian arguments against this, it should be obvious that there reaches a point where the marginal return for additional hours is negative—where adding extra hours reduces total productivity. Experiments like this are designed to find out where that inflection point is, and the evidence that's coming in so far suggests that the inflection point is somewhere below 40 hours. More research is needed, but that's exactly what is happening.
- bluesign 4y ago
  40 hours work vs 40 hours office is not the same thing though. Maybe diminishing return starts at 30 hours of work, but still you can benefit from some relaxed schedule at the office. 30 hours work at 40 hours office time vs 30 hours work at 30 hours office time would have different outputs for sure.
  - akiselev 4y ago
    If those 10 relaxed hours actually mattered there’d be a measurable productivity drop. If it’s not measurable or significant, then those 10 hours don’t matter and we should get them back for stuff that does.
    - pc86 4y ago
      No company is measuring hourly productivity, especially in anything beyond the lowest levels.
      - lolinder 4y ago
        It doesn't matter—if a company joins in one of these experiments and drops everyone to 32 hours, we should see a decrease in company-wide productivity if OP is correct that the downtime is useful. If it's not useful, then we should see stable or increased productivity (which is what most companies are reporting).
Moissanite 4y ago
I think it helps to start with the assertion that benefits from economic/productivity growth have accrued to owners, not workers, and that a correction is overdue - if you don't agree with that, discussion over working fewer hours feels moot. Going forward with the idea that workers deserve a bit of a break: > sounds like it's entirely wishful thinking and in a few years will be having the same amount of wasted hours in those days I can see that to some extent, but if expectations stay the same I think "trimming the fat" would be a more likely outcome - i.e. more push-back on pointless meetings and other inefficiency. I'd expect it to take a longer time than just a few years for apathy to set in - at which point we would have more data about the effectiveness of the plan over time. > Are there any actual evidence that that optimum middle ground is 4 days and not 3, or 5? I think lots of us have anecdata that "meaningful work done" does not drop by 20% (if at all) in a 4-day week, and satisfaction increases substantially. I can imagine a future push to reduce further to 3 days - but isn't that a realistic expectation given further productivity-boosting technology will arrive?
- poszlem 4y ago
  >I think it helps to start with the assertion that benefits from economic/productivity growth have accrued to owners, not workers, and that a correction is overdue - if you don't agree with that, discussion over working fewer hours feels moot. That is exactly what I meant by this being a political project to which we try to will evidence into existence.
ozim 4y ago
In my opinion, especially when it comes to individual employees "productivity" is overrated.
unity1001 4y ago
> but I really struggle to understand how working fewer hours will not result in loss of productivity Microsoft Japan did 4 day workweeks and saw 40% increase in productivity. https://mashable.com/article/microsoft-japan-4-day-work-week-trial-3-day-weekend?europe=true https://mashable.com/article/microsoft-japan-4-day-work-week... Its likely because a 3 day weekend allows people to totally disconnect from work and rest. It even allows you to travel, visit family etc.
- barking_biscuit 4y ago
  They haven't even mastered implementing standard 40 hour weeks yet. Wait until they see the productivity gains from those.
somedude895 4y ago
I don't really get it either. Sure I'd like to work less and get paid more, but if employees can do 5 days of work in 4 days, doesn't that mean that you should fire 20% of your staff? I could see it have no effect at first while people appreciate the extra time off, so they work harder for four days, but if it becomes the norm that would normalize and productivity would slowly drop across that society.
- lolinder 4y ago
  > Sure I'd like to work less and get paid more, but if employees can do 5 days of work in 4 days, doesn't that mean that you should fire 20% of your staff? No, because the argument for the four-day work week is that the extra day takes 20% more time but does not contribute anything like 20% more productivity. People are worn out by the time they get to Friday, and so 5 people working 4 days can get more done than 4 people working 5 days, even though "man-hours" is the same.
twblalock 4y ago
> I assume there is some sort of middle ground between working too much and working too little. Are there any actual evidence that that optimum middle ground is 4 days and not 3, or 5? That's the problem with this whole thing. People don't have a rationale for it. They just want to work fewer hours. If the 4-day week happens, we will see the same arguments being made for the 3-day week, because there is no actual basis for any of this: people will always want to work fewer hours than they work now.
- lolinder 4y ago
  You can disagree with the rationale, but if you think there isn't one then you didn't read the article or any of the comments, you're just sharing your knee-jerk reaction.
didibus 4y ago
Before productivity, this is also about simple social quality of life. I know we often think in the smaller system of capitalism, but the point of any economic system is to bring overall better quality of life to citizens. A lot of people are now observing that additional work doesn't bring additional quality of life, and so the next push for improved quality of life now might come at reconsidering the 5 day work week and maybe making it 4. Now about productivity, there's a few arguments: 1. Reducing wasted time. Lots of work is inefficient, lots of meetings going in circles, distractions, etc. If you have only 4 days, you hope that it will push companies to reduce the waste. 2. Rest/leisure and productivity have correlations. Maybe an extra day of rest can boost people's work days and actually make them more productive. 3. Most type of work where people are considering 4 day work week is creative work. Productivity often comes simply from better ideas and better decisions. An extra work day doesn't really affect the quality of your decisions and the potential of your ideas. 4. Most type of work where people are considering 4 day work week have uneven value output. Something you did in the first quarter on its own can provide enough value to justify your entire year's salary.
fleddr 4y ago
Two very simple answers, which I won't bother to back up with any science. 1) Many office workers spent some 50-80% of their work hours on overhead (meetings, email), leaving very little time for actual focused tasks, things that actually need to get done. When you work one day less, you just optimize the overhead part whilst still outputting the same net productivity. 2) The human mind cannot be cognitively productive 5 x 8. Consciously or subconsciously, you'll bleed downtime into your day, quite a lot of it. Pretending to be busy, sitting out the time. Not because you're a slacker, you're just human. Office work is deeply unnatural.
- itake 4y ago
  Whenever I have 1 less day (like holiday weeks), my other days suffer. Just because Friday is a holiday doesn't mean the regularly scheduled meetings can just be skipped.
- lelanthran 4y ago
  > Many office workers spent some 50-80% of their work hours on overhead (meetings, email), leaving very little time for actual focused tasks, things that actually need to get done. When you work one day less, you just optimize the overhead part whilst still outputting the same net productivity. If it were that easy to cull out the overhead it'd be done by now in the existing 5-day week. I can see no reason (and none is presented in any of the comments) why moving to a 4-day week will suddenly reduce pointless meetings. It's asserted as fact multiple times, but it isn't.
  - fleddr 4y ago
    "If it were that easy to cull out the overhead it'd be done by now in the existing 5-day week." This is a misunderstanding of the dynamic. Collaboration and overhead inflates to whatever the capacity is. There's no strong force to stop it, bizarre as that is. When you reduce capacity, the counter force is there. I normally do 10 meetings but can now only afford 8.
    - lelanthran 4y ago
jokethrowaway 4y ago
The theory is that the weekend is not enough to "recharge" and that productivity wanes over the week. Now, I can buy the theory of very unproductive fridays when nothing gets done, but I think a better model would be to just work 6 hours instead of 8.
- pc86 4y ago
  Why? Other than 5x6 is less than 4x8.
  - d3ckard 4y ago
    You’re working less, but for 5 days, so you get more “fresh hours”.
octodog 4y ago
You are quick to dismiss this as political. Counterpoint: what makes 40 hours a week the sweet spot? Why is 40 more productive than 50?
- poszlem 4y ago
  I absolutely think that the 40 hours a week were chosen because of political reasons. That doesn't mean we should work for 7 days a week, or that the fact that we work 40 hours a week is a problem in any way. The only thing I don't understand and have trouble with is people claiming that 4 days work week somehow results in them doing more work than they do in 5 days. To me it sounds like people have decided that they want to work less (totally reasonable) and then try to use "trust the science" method to make it happen.
brightball 4y ago
There's a business that I know which had a 4 day work week and all the employees just moonlighted at other jobs on Friday to make extra money...so they just opened for a half day on Fridays to give people the option to make more money there. It was an actual service based company where more hours meant more customers served.
pc86 4y ago
There are a couple incorrect assumptions in this. First and foremost, this discussion doesn't always mean 4x8 hour days, it could very well mean 4x10. Same number of hours, in fewer days. By your admission this should be the same amount of productivity, however you define that. You're also admitting it's reductio ad absurdum, so why not just stop with that? Clearly there is some maximal point of work-per-unit-of-time (e.g. productivity). 0 hours of work will be 0 production by definition, and 40 is whatever it is now, P. Who's to say that 38 hours instead of 40 wouldn't be 1.01P? Who's to say that 45 hours wouldn't be 0.9P? Being so against these types of experiments presupposes that we've magically landed on the 40 hour work week and it just so happens to be the maximal point of productivity. The odds of that being that case are pretty small. > Are there any actual evidence that that optimum middle ground is 4 days and not 3, or 5? Maybe that's the whole point of doing things like this? You don't get evidence like this in a lab or in a thought experiment, you get it by having companies try this out and see what happens to their revenue, their worker retention, their customer base, etc. Maybe 32 hours a week will result in less total revenue but a wildly loyal employee and customer base, that could be translated into a larger business in the long term even with higher per capita expense? > What I find much more interesting is switching from a 7 day week to something else entirely, for example working on: Monday, Tuesday, Wednesday is free, Thursday, Friday, Saturday, Sunday is free. I can see how that might result in people being more productive, as they still work the same amount of hours, but they don't get as exhausted as before. This is still a 7 day week you're just broken up the weekend. I'm not sure how that results in people "not as exhausted."
doliveira 4y ago
Oh yes, of course, it's others who are being political, obviously not me.
mettamage 4y ago
Edit: I simplified my math. I know there are 24 hours of work in a day. It's not about that. The point is about rhythm. 7 days is 100% If you'd work 7 days, there's no downtime to recover. You simply just tear into your reserves, and get less productive each week until you hit diminishing "returns" in being less productive, getting to some low productive apathy state. It's productivity rock bottom. There are people who can manage this but very few can. 6 days 86%. Now you can rest for a day. Great! But there's still little time for socializing and other stuff in life. There's no way of flourishing at all. Also, if there's trouble but not enough trouble (e.g. bad sleep), then you'll be using that day and there's no socialization at all that week. Or time to spend on your hobbies. 5 days is 71%. Now you can devote 29% of every week on free time. Literally 29% of your life is free. You can now absorb fairly big shocks that aren't covered in illness protection plans. You also have time to get into a hobby. So why 4? The cyclical nature of the week makes it to be 57%. 43% is left to free time. I'm working this amount. If I include my vacation days with it, I work an exact 50% and am free 50%. I have sleep issues that no doctor cares to know about. My free day is on a Wednesday. If my sleep is screwed over then I can rest all day during a Wednesday or a Saturday. Sunday is always left over for free time. If I have a good week of sleep, then it can happen that I feel a bit bored. I have too much free time. It results in an iron clad focus on work. I've worked 5 days per week. I never had an iron clad focus as I was always struggling with sleep. If my sleep was screwed over on Monday, then I'd need to suffer until Friday. Now I only need to suffer until Wednesday and sometimes I even swap days and don't have to suffer at all. So that's a simple example of how it improves my focus. It's an example of how I'm probably more productive on 4 days than 5. Why more? Productivity drops by 50% for programmers with severe sleep deprivation. Different sectors and situations may have different results. But I'd suggest to try and sketch out different scenarios where it does and doesn't work. So why not 3? Well maybe 3. I can tell you why not 2, because it's extreme enough for me to see why. The context of work starts to fade. Your subconscious starts to deal with issues less to not at all (in the context of programming). It takes way longer to warm up. Why is this the case with 2? Because 2 days of work is only 29% of your week. Your identity will be formed around what you'll do in your free time. Work will become a "side thing". You will be amazingly well rested to work, provided you can manage your life well. But the extra increase in focus won't make up for it. The switch between 5 to 4 days may in certain cases may not up for it either, but in my particular case it's clear that it does.

vorpalhex 4y ago

We need to do experiments and gather data to test hypothesis. This is one of those experiments.

adamckay 4y ago

The no loss of productivity can be a combination of multiple things: a) There is loss in productivity but it isn't (or can't be) properly measured or does not make an impact on the business, e.g. a help desk responds to customers with 1 business day rather than 4 business hours. b) People are more motivated (including it being a novelty) so employees are eager to work harder in their reduced hours to ensure they can continue a 4-day working week. If this becomes the norm after a while you may see this slack off. c) Lots of people are doing busy-work or "bullshit tasks" which do not actually affect business productivity or are simply just looking busy and procrastinating, e.g. office workers browsing Twitter, Reddit or HN for a short time every couple of hours which is eliminated. It highlights saying "don't confuse activity with achievement/productivity".

lolinder 4y ago

Most systems don't have a nice, clean, linear relationship. You did a reductio ad absurdum in one direction, let's do it in the other: if hours worked directly translates to productivity, then we should be able to add more hours and continually get more productivity. Why not add Saturdays and Sundays back in? Then we can go to 10 hour workdays. Maybe 12 hours? Even aside from the humanitarian arguments against this, it should be obvious that there reaches a point where the marginal return for additional hours is negative—where adding extra hours reduces total productivity. Experiments like this are designed to find out where that inflection point is, and the evidence that's coming in so far suggests that the inflection point is somewhere below 40 hours. More research is needed, but that's exactly what is happening.

bluesign 4y ago
40 hours work vs 40 hours office is not the same thing though. Maybe diminishing return starts at 30 hours of work, but still you can benefit from some relaxed schedule at the office. 30 hours work at 40 hours office time vs 30 hours work at 30 hours office time would have different outputs for sure.
- akiselev 4y ago
  If those 10 relaxed hours actually mattered there’d be a measurable productivity drop. If it’s not measurable or significant, then those 10 hours don’t matter and we should get them back for stuff that does.
  - pc86 4y ago
    No company is measuring hourly productivity, especially in anything beyond the lowest levels.
    - lolinder 4y ago
      It doesn't matter—if a company joins in one of these experiments and drops everyone to 32 hours, we should see a decrease in company-wide productivity if OP is correct that the downtime is useful. If it's not useful, then we should see stable or increased productivity (which is what most companies are reporting).

Moissanite 4y ago

I think it helps to start with the assertion that benefits from economic/productivity growth have accrued to owners, not workers, and that a correction is overdue - if you don't agree with that, discussion over working fewer hours feels moot. Going forward with the idea that workers deserve a bit of a break: > sounds like it's entirely wishful thinking and in a few years will be having the same amount of wasted hours in those days I can see that to some extent, but if expectations stay the same I think "trimming the fat" would be a more likely outcome - i.e. more push-back on pointless meetings and other inefficiency. I'd expect it to take a longer time than just a few years for apathy to set in - at which point we would have more data about the effectiveness of the plan over time. > Are there any actual evidence that that optimum middle ground is 4 days and not 3, or 5? I think lots of us have anecdata that "meaningful work done" does not drop by 20% (if at all) in a 4-day week, and satisfaction increases substantially. I can imagine a future push to reduce further to 3 days - but isn't that a realistic expectation given further productivity-boosting technology will arrive?

poszlem 4y ago
>I think it helps to start with the assertion that benefits from economic/productivity growth have accrued to owners, not workers, and that a correction is overdue - if you don't agree with that, discussion over working fewer hours feels moot. That is exactly what I meant by this being a political project to which we try to will evidence into existence.

ozim 4y ago

In my opinion, especially when it comes to individual employees "productivity" is overrated.

unity1001 4y ago

> but I really struggle to understand how working fewer hours will not result in loss of productivity Microsoft Japan did 4 day workweeks and saw 40% increase in productivity. https://mashable.com/article/microsoft-japan-4-day-work-week-trial-3-day-weekend?europe=true https://mashable.com/article/microsoft-japan-4-day-work-week... Its likely because a 3 day weekend allows people to totally disconnect from work and rest. It even allows you to travel, visit family etc.

barking_biscuit 4y ago
They haven't even mastered implementing standard 40 hour weeks yet. Wait until they see the productivity gains from those.

somedude895 4y ago

I don't really get it either. Sure I'd like to work less and get paid more, but if employees can do 5 days of work in 4 days, doesn't that mean that you should fire 20% of your staff? I could see it have no effect at first while people appreciate the extra time off, so they work harder for four days, but if it becomes the norm that would normalize and productivity would slowly drop across that society.

lolinder 4y ago
> Sure I'd like to work less and get paid more, but if employees can do 5 days of work in 4 days, doesn't that mean that you should fire 20% of your staff? No, because the argument for the four-day work week is that the extra day takes 20% more time but does not contribute anything like 20% more productivity. People are worn out by the time they get to Friday, and so 5 people working 4 days can get more done than 4 people working 5 days, even though "man-hours" is the same.

twblalock 4y ago

> I assume there is some sort of middle ground between working too much and working too little. Are there any actual evidence that that optimum middle ground is 4 days and not 3, or 5? That's the problem with this whole thing. People don't have a rationale for it. They just want to work fewer hours. If the 4-day week happens, we will see the same arguments being made for the 3-day week, because there is no actual basis for any of this: people will always want to work fewer hours than they work now.

lolinder 4y ago
You can disagree with the rationale, but if you think there isn't one then you didn't read the article or any of the comments, you're just sharing your knee-jerk reaction.

didibus 4y ago

Before productivity, this is also about simple social quality of life. I know we often think in the smaller system of capitalism, but the point of any economic system is to bring overall better quality of life to citizens. A lot of people are now observing that additional work doesn't bring additional quality of life, and so the next push for improved quality of life now might come at reconsidering the 5 day work week and maybe making it 4. Now about productivity, there's a few arguments: 1. Reducing wasted time. Lots of work is inefficient, lots of meetings going in circles, distractions, etc. If you have only 4 days, you hope that it will push companies to reduce the waste. 2. Rest/leisure and productivity have correlations. Maybe an extra day of rest can boost people's work days and actually make them more productive. 3. Most type of work where people are considering 4 day work week is creative work. Productivity often comes simply from better ideas and better decisions. An extra work day doesn't really affect the quality of your decisions and the potential of your ideas. 4. Most type of work where people are considering 4 day work week have uneven value output. Something you did in the first quarter on its own can provide enough value to justify your entire year's salary.

fleddr 4y ago

Two very simple answers, which I won't bother to back up with any science. 1) Many office workers spent some 50-80% of their work hours on overhead (meetings, email), leaving very little time for actual focused tasks, things that actually need to get done. When you work one day less, you just optimize the overhead part whilst still outputting the same net productivity. 2) The human mind cannot be cognitively productive 5 x 8. Consciously or subconsciously, you'll bleed downtime into your day, quite a lot of it. Pretending to be busy, sitting out the time. Not because you're a slacker, you're just human. Office work is deeply unnatural.

itake 4y ago
Whenever I have 1 less day (like holiday weeks), my other days suffer. Just because Friday is a holiday doesn't mean the regularly scheduled meetings can just be skipped.
lelanthran 4y ago
> Many office workers spent some 50-80% of their work hours on overhead (meetings, email), leaving very little time for actual focused tasks, things that actually need to get done. When you work one day less, you just optimize the overhead part whilst still outputting the same net productivity. If it were that easy to cull out the overhead it'd be done by now in the existing 5-day week. I can see no reason (and none is presented in any of the comments) why moving to a 4-day week will suddenly reduce pointless meetings. It's asserted as fact multiple times, but it isn't.
- fleddr 4y ago
  "If it were that easy to cull out the overhead it'd be done by now in the existing 5-day week." This is a misunderstanding of the dynamic. Collaboration and overhead inflates to whatever the capacity is. There's no strong force to stop it, bizarre as that is. When you reduce capacity, the counter force is there. I normally do 10 meetings but can now only afford 8.
  - lelanthran 4y ago

jokethrowaway 4y ago

The theory is that the weekend is not enough to "recharge" and that productivity wanes over the week. Now, I can buy the theory of very unproductive fridays when nothing gets done, but I think a better model would be to just work 6 hours instead of 8.

pc86 4y ago
Why? Other than 5x6 is less than 4x8.
- d3ckard 4y ago
  You’re working less, but for 5 days, so you get more “fresh hours”.

octodog 4y ago

You are quick to dismiss this as political. Counterpoint: what makes 40 hours a week the sweet spot? Why is 40 more productive than 50?

poszlem 4y ago
I absolutely think that the 40 hours a week were chosen because of political reasons. That doesn't mean we should work for 7 days a week, or that the fact that we work 40 hours a week is a problem in any way. The only thing I don't understand and have trouble with is people claiming that 4 days work week somehow results in them doing more work than they do in 5 days. To me it sounds like people have decided that they want to work less (totally reasonable) and then try to use "trust the science" method to make it happen.

brightball 4y ago

There's a business that I know which had a 4 day work week and all the employees just moonlighted at other jobs on Friday to make extra money...so they just opened for a half day on Fridays to give people the option to make more money there. It was an actual service based company where more hours meant more customers served.

pc86 4y ago

There are a couple incorrect assumptions in this. First and foremost, this discussion doesn't always mean 4x8 hour days, it could very well mean 4x10. Same number of hours, in fewer days. By your admission this should be the same amount of productivity, however you define that. You're also admitting it's reductio ad absurdum, so why not just stop with that? Clearly there is some maximal point of work-per-unit-of-time (e.g. productivity). 0 hours of work will be 0 production by definition, and 40 is whatever it is now, P. Who's to say that 38 hours instead of 40 wouldn't be 1.01P? Who's to say that 45 hours wouldn't be 0.9P? Being so against these types of experiments presupposes that we've magically landed on the 40 hour work week and it just so happens to be the maximal point of productivity. The odds of that being that case are pretty small. > Are there any actual evidence that that optimum middle ground is 4 days and not 3, or 5? Maybe that's the whole point of doing things like this? You don't get evidence like this in a lab or in a thought experiment, you get it by having companies try this out and see what happens to their revenue, their worker retention, their customer base, etc. Maybe 32 hours a week will result in less total revenue but a wildly loyal employee and customer base, that could be translated into a larger business in the long term even with higher per capita expense? > What I find much more interesting is switching from a 7 day week to something else entirely, for example working on: Monday, Tuesday, Wednesday is free, Thursday, Friday, Saturday, Sunday is free. I can see how that might result in people being more productive, as they still work the same amount of hours, but they don't get as exhausted as before. This is still a 7 day week you're just broken up the weekend. I'm not sure how that results in people "not as exhausted."

doliveira 4y ago

Oh yes, of course, it's others who are being political, obviously not me.

mettamage 4y ago

Edit: I simplified my math. I know there are 24 hours of work in a day. It's not about that. The point is about rhythm. 7 days is 100% If you'd work 7 days, there's no downtime to recover. You simply just tear into your reserves, and get less productive each week until you hit diminishing "returns" in being less productive, getting to some low productive apathy state. It's productivity rock bottom. There are people who can manage this but very few can. 6 days 86%. Now you can rest for a day. Great! But there's still little time for socializing and other stuff in life. There's no way of flourishing at all. Also, if there's trouble but not enough trouble (e.g. bad sleep), then you'll be using that day and there's no socialization at all that week. Or time to spend on your hobbies. 5 days is 71%. Now you can devote 29% of every week on free time. Literally 29% of your life is free. You can now absorb fairly big shocks that aren't covered in illness protection plans. You also have time to get into a hobby. So why 4? The cyclical nature of the week makes it to be 57%. 43% is left to free time. I'm working this amount. If I include my vacation days with it, I work an exact 50% and am free 50%. I have sleep issues that no doctor cares to know about. My free day is on a Wednesday. If my sleep is screwed over then I can rest all day during a Wednesday or a Saturday. Sunday is always left over for free time. If I have a good week of sleep, then it can happen that I feel a bit bored. I have too much free time. It results in an iron clad focus on work. I've worked 5 days per week. I never had an iron clad focus as I was always struggling with sleep. If my sleep was screwed over on Monday, then I'd need to suffer until Friday. Now I only need to suffer until Wednesday and sometimes I even swap days and don't have to suffer at all. So that's a simple example of how it improves my focus. It's an example of how I'm probably more productive on 4 days than 5. Why more? Productivity drops by 50% for programmers with severe sleep deprivation. Different sectors and situations may have different results. But I'd suggest to try and sketch out different scenarios where it does and doesn't work. So why not 3? Well maybe 3. I can tell you why not 2, because it's extreme enough for me to see why. The context of work starts to fade. Your subconscious starts to deal with issues less to not at all (in the context of programming). It takes way longer to warm up. Why is this the case with 2? Because 2 days of work is only 29% of your week. Your identity will be formed around what you'll do in your free time. Work will become a "side thing". You will be amazingly well rested to work, provided you can manage your life well. But the extra increase in focus won't make up for it. The switch between 5 to 4 days may in certain cases may not up for it either, but in my particular case it's clear that it does.