I think this all shows that for many, but definitely not all, jobs there is a finite amount of productive time that people have to give. You can make people be at the office for crazy hours (looking at you japan), but you don't actually squeeze that much more useful work out of people. I think this is especially true of work that requires alot of mental focus like problem solving or other creative type work. Much of that happens in down-time where your mind is working on it behind the scenes. That's why people have breakthroughs when going for a walk or taking a shower. So the 'down-time' is just as important as the active time. Similar to physical exercise - the recovery phase is as important than the exertion phase.