just my 2 cents, if you're a 6 day a week shooter, you ought to change them every 6 months. if you're not, once a year. if you're shooting 45# its not as important as if you're shooting 70#. some of the newer materials (452x or ultracam) won't give the warning signs that 8125 will. i see guys waxing down strings that look like fuzzy yarn made out of 8125 and shooting, but with 452x i wouldn't do this. its just not worth it.