Target sells balls for $2.09 a can, so for me its worth opening a new can whenever I feel the balls are getting too old.
I used to play with some older guys in the park on Sunday afternoons. They loved to bring out some of the oldest balls they had in their bag. Harder for me to use my power advantage and old balls are easier to control for a pusher. Drop shots are very effective. I never let on that I knew they were using dead balls and they always had fun.
"It is no measure of health to be well adjusted to a profoundly sick society.” ~ Jiddu Krishnamurti