At my school Greeks wear their letters every Friday... at least. We are proud of our letters. Any time I dress up nicely, I wear my badge. I wore it today to the basketball game because I had to dress up to sing the national anthem, and I wore it like twice this week because I had to dress up a lot.
I know that the TKEs here wear their badges if they don't wear their letters every Friday, and I see many other fraternities wearing theirs when they are dressed appropriately. But we all wear letters all the time... hell I have enough to go through two weeks without having to do laundry!