We'll cut you some slack because you're relatively new here, but having 20-30 cards that you don't use is not that unusual around here.

I have a box full of cards that I've had and later canceled, as well as a half-dozen in play at any given time. Depends on the promos.

Having said that - opening and closing accounts can look a little dicey to lenders. However, having a card you don't use but has no annual fee is much better used by sitting in a drawer rather than cancelling, because it adds to the "ageing" of your credit score.