Having been quite the slacker, I assure you there are massively diminishing returns to leisure time, unless you turn it into work. If you don't get anything done, you feel worthless. Maybe 20 hours a week is enough, but no work at all isn't good for you. Rioting in the streets is exactly what the welfare class of Britain did mere months ago.

Art and study could certainly be more heavily subsidized, though. But I would count those as types of work.