excellent question and one we all think about IMO. but when your ketchn crappie or BG it can be hard to leave a good bite no matter what the size as it is FUN! But if your looking for eaters then you do have to move. on my home lake when the spawn is on stays on for quite a while and you ketch one 4 to 7 incher after the other but don't get into bigger males even when you move. so it's a mystery.