To be completely honest, how this can give positive results is beyond me. Personally I use my free time for side projects except only for social events on weekends. If my work time was reduced to say 6 hours, or alternatively to a 4-day work week, I'd use more time on side projects which are the same in nature as my main job. I don't think that would affect my productivity neither for the main job nor for the side projects, it would just change the time allocation and therefore the amount of work done on each side. That's all. I'm in my early 50s and I just can't stop doing this.
While I can imagine a lot of people in the world would only applaud to any official reduction of work time, again, I just don't understand how that can increase their productivity at work.
So the fact that the experiment worked at Microsoft only says that Microsoft is terribly unproductive otherwise. Which should be true for the majority of large organizations.
I suspect you would understand if you spent less time at work or doing side projects and more time resting.. some insights come after having some time to get bored.
While I can imagine a lot of people in the world would only applaud to any official reduction of work time, again, I just don't understand how that can increase their productivity at work.