I read a couple of responses that referred to changing tires, so somehow I've got to compare changing needles to old tires
When I was dating (many many years ago) Dad always checked the tires on the vehicle the guy was driving, I guess he thought if they had good tread, their priorities were in the right order.
I never discussed needles with him, but I do know that since I've been married, whenever we borrowed anything from him we had to fix it first
If I had to guess when I change needles, I guess it's when I hear the popping