I usually replace mine every 3-4 years. I also don’t shoot a lot I’d say under 200 shots a year. Twisted X bowstrings in Oklahoma builds some great string though.
I used to go until my cams changed orientation from where I have them marked, or the feel of the bow changed. But a few years ago I had a yoke loop break right before full draw. Each side of the yoke has half the number of strands, so should be replaced twice as often as bows without yokes I imagine. I estimated I had about 30k shots on them, I obviously pushed them too far. But for my other bows it's pretty obvious when something changes and it's time.
Most of the time 3-4 years depending on how it's holding up. I've been shooting a lot more now since the lock down so I may have to go to 2-3 years. My local shop recommends GAS bowstrings and says they hold up much better than some others, so we'll see. I've had new one on for about 5 months and it still looks great so far after average of 50 shots per day.
Roughly 9000-10,000 shots for me. On my open bow that's going to be about two sets a year, but it truly depends on your tolerance for moving strings. Hunting bow, I normally change about once a year
I'm every 4-8months with bcy 452 material, since switching to vec 99, I'm on 8months no creep/string twisting tiny bit of fraying. Might be me, but I love that material.