When is it appropriate to wear make-up?

I use to wear SO much make-up every single day. Now-a-days, I feel like it's a waste of money, time, and a real hle to have to wash it off every. single. day. I feel like when I go back to school in the fall I'm not even gonna bother wearing make-up to school... When do you think it's appropriate to wear make-up? I think I'm gonna stop wearing it on the weekdays and just wear it on the weekends so I can just focus on school and not really care about whether or not people think I'm 'good-looking'. When do you wear make-up?