Is it better to get up because it's time, or because you're well-rested?

When is it time to get married? When is it time to buy your first home? When is it time to eat? When is it time to use the bathroom (i.e. urinate, defacate, etc.)? When is it time to retire? Is it better for a culture and society to encourage people to do things "on time," or to do things when actually ready??