Had to actually play a game and hold ctrl to realize that I just don't actually hit ctrl while moving much. Guess I don't play anything in which it's necessary. I mean it's necessary to crouch in L4D2 to get good accuracy with some weapons, but I tend to stay still while shooting with them since there's just no reason to move around until I've killed whatever I need to. When I do move, I tend to move the other fingers over so I have middle on W/S.

So I probably need to switch over to the other method if I were to ever play games in which crouching is necessary.