Mine is partly informed by the desire to have sufficient time to figure out what to do with myself on said rainy Sunday afternoon. Also by the desire to be able to do Nothing on said afternoon if I want to, without it exacting an opportunity cost.

Actually, that might be exactly what I want, or at least a concise description of one of the things I want: For a particular use of time to have zero opportunity cost. I wouldn't be as bitter about going to work for eight to ten hours a day if that didn't mean eight to ten hours I can't use doing something more interesting/entertaining/relaxing/whatever.