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

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".