Here are some factors to think about... How often do you wax your string? How much shooting do you do? What kind of bow do you have?
The last one is pretty important. The Cams on many of the newer bows have some fairly sharp curves that will wear you string out quickly. The speed comes at a price. the 2 things you should do on a regular basis is 1 wax your string, 2 inspect the serving on your strings. The serving is the "wrap" around the actual bow string. it is located where you knock the arrow, and also where the pulleys travel over the string. The serving is there to protect the string. You can have your strings re served, and i have had that done. IF you string has lots off fiber comeing off it and is looking more like yarn than dental floss then its likely time to get a new string, and start waxing the new one to make it last.
I'm shooting about 750-1000 a year on my switchback and have been shooting the string for about 5 years now. I take good care of my string, and i will likely change the string out before hunting season this year.
