Exactly! I think of this every time this subject comes up and I always come to think of the scene from Something About Mary [1]

[1] https://youtu.be/rnso4nfdM9w

I also think the productivity gain or lack of loss comes from excitement and a feeling of responsibility for having the extra day off. It's mentioned in the article

>“The biggest concern from an employer point of view is ensuring that the full-time introduction of the policy doesn’t lead to complacency, with the risk that people’s productivity will slip back,” Barker said.

“To guard against this happening we’ve spent a lot of time making sure every person in every team has their own plan as to how they’re going to maintain and even improve their productivity.”

I think this makes sense but, as time passes and 4 days becomes the norm the feeling of excitement and responsibility will fall and output will follow. If everyone has a 4 day work week we will probably be as lazy as we are now in our 5 days.

Sounds like a win to me!

At that point we can start experimenting with a 3 day workweek, and find that it too doesn’t reduce productivity.

At some point in time, we’ll find out that all our work is essentially automated, and the step from one to zero days of work will seem reasonable.

There is a topic on reddit now which can shed some light on this question.

How Many Productive Hours in a Work Day? Just 2 Hours, 23 Minutes... https://www.reddit.com/r/Economics/comments/as3cyv/how_many_...

Actually, Tim Ferris wrote a book called "The 4-Hour Workweek" with the goal of more people achieving the title. It is more oriented at breaking free of normal work habits than a scientific study of optimal productivity though.

The pills and books he sells to achieve his 4-hour work week make me suspicious of the methodology. Only so many can sell shovels to the gold miners before the market is saturated.

Something tells me Tim Ferris works a lot more than 4 hours a week himself.

His podcasts had him on for about six hours weekly iirc.

I recall half of that book was about outsourcing your work.

It’s only a 4-hour workweek for you. There’s still someone doing the work.

Personally, my optimum is three 8-hour days a week.

I have also found they need to be consecutive.

It depends on the person and job, of course. I've worked with people who added net negative productivity for the company, so for them, the breaking point would actually be 0.