Sleep isn't fun enough to be worth 8hr every day. But we try to do it anyway because it makes non-sleep hours better. That's the sort of thing OP is talking anout.
No but you're justifying the non-work time again - I'm saying it's the _work_ time that needs to be justified (by what it allows me to do that costs actual money - okay, buy a bed, sure) _not_ vice versa.
I'd like to think that, were I not salaried, I'd work only as much as i needed in order to do whatever it was that I wanted to do with the rest of my time - not relax in a way that allowed me to work as much as possible.
Of course, in reality it's a slightly harder optimisation problem than presented, since time is a factor too, and maybe you can't afford to do what you want to do leisurely for 4 days a week, working 3, but it can be done at 3.5 each way.
