I always start off playing brand new balls every round. I usually start with a new dozen balls to play and 3-4 that are used in good shape for particularly troublesome tee shots. If I scuff one, I take it out of play and put it in the bag to give to my 10 year old. I’ve gotten to the point where I can get through most rounds with about 2-3 balls if I’m playing decent golf. I have one in my pocket to play and the other two from the sleeve in the cart. If I have to go get another new sleeve out of the bag I’m still good. Whenever I get down to 2 new sleeves, I put another new dozen in the bag.