Do you prefer keeping a small number of decks ready, or a large number of decks?

Im just curious. I finally decided to disassemble a deck I own to upgrade a couple of my other decks that would utilize the cards better, and I partially wonder how often others have to do the same. My playgroup will frequently get on to me for doing this, when the lot of them carry more cards on their person than I've owned in my life (I really don't make enough money to spend on cards), but then ask me why I don't have X card in my deck because it'd work so much better than what I have when that card is in my other deck that they were just getting on to me for disassembling. I usually prefer to keep my number of decks low to avoid doing this, or trading off a pile of my own cards just to get a copy of one I already have in use, but what about you? Do you prefer to have a small number of decks, or a large number of decks?