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 num

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."