I wear them when i'm working ( which is every day ). I have two pair. One at the office, and one at home. I don't wear them out at all.
It's the Fluorescent lighting, and screen lights that bother me most. They filter it out enough that i don't sort of struggle with focus, and the headaches have stopped completely.
If I was outside as much as I am inside I might try to wear them more outdoors, but the sad reality is I'm behind the screen much much longer than I am in the sun.