I would assume that there’s a balance to this. At some point the reduction of hours will result in a loss in productivity. You can do 5 days of work in 4 days if you’re better rested and more focused, but this might be less true in 3 days. I mean if studies show that there’s isn’t a dip productivity and that it improves well being, then sure, that would be great but I think it’s likely than a 4 day work week.