Some go every week, some go after every shed, some once per season (I have heard). I've had mine for about 6 or 7 months and have only found actual physical feces about 3 or 4 times.
They are all different. As long as s/he is passing urates, everything should be fine.
Don't let anyone, ever, make you feel like you don't deserve what you want. - Heath Ledger