I see people say you should change your string after it loses its bounce, but that’s like 20 minutes. Every time I see this, I wonder whether the suggesting person actually yoyos, or at least if the suggester uses different string. With bulk strings at ~20c/string, that’s like 1c/minute; for 2h of yoyoing per day that’s 6 strings or $1.20, or $36/month. That’s not horrible, but it seems like a lot to spend on strings. I usually just change when I get a bad knot.
I’m using 100% poly type 6 string. I’ve played it for several hours, and it’s getting really frayed, I mean reeeally frayed. It’s about as furry as my dog. And I don’t notice any problems with it. I must be missing something.