Ok will I know this isnt good but how often doyou need to change your string? Becuase I only have 1 string untill wednesday or thurdsday :'(…I use 100%poly and im on intermidiete section I yoyo about 1-2 hours a day and on weekends up to 3.5-4 hours???
Sorry if theres already a topic on this… :-X
It depends on you. We really cant give you an allotted time. Change it when it is dirty, frayed, or not playable. Just change it when you feel you need to 
it stinks ive been using the same string since wednesday and i wont have more till this wednesday/thursday :‘( :’(
When ever looks dirty, burnt, like that stuff. When it get’s warn down i look for dirty, and the diffrence in the size from fresh string. I would say swich every day, but if you have 1 string left use that till more come. 
~Steven
For Polys, they usually last 2-3 days with 6-8 hours of play. It really depends on how you play though.
Just use your string until you get a new one. But after that remember to always change it one you have a knot. I use YYN Highlights and change them about once every one or two days.
I just make my own, never saw store string except for the ones that come with yoyos. If you want to make it, look here (I’m linking a lot today)
Usually you should replace your string for the reasons these guys said. Also change it when the yo-yo is super unresponsive and won’t come up even after a bunch of times. Also when you feel the string is tearing at your skin.
~Spin On!
You can change your string after it broke,and you can also
change your the string is too thin.
Happy Throwing! =]
Or when you can see tears, or when your yoyo flew away!!!
ya when i started playin. i was doin and around the world and the string broke, so my fast was rifling about 30 feet in the air.
so change your string when you think it is almost finished, also i can brake my string in a day or 3. it depends on how thick it is.