Yep every day! I don't think they do get bored of them, they seem to eat enough grass in the wild without getting bored, and mine still go bonkers for their pellets!
I feed a small amount of pellets twice a day (mainly so I can check they are both eating ok, before I go, and when I get home from work) and veg last thing at night before bed, so they have something to munch on when they are shut in overnight.