For those with 20 plus guitars it's hard to remember when they were changed last. I dont personally change mine often because it adds up. I've heard said that you should change them at least every month if you're playing that guitar daily. I dont know. I dont usually hear them go bad either. Buy usually I break a few modding and replace what I have to. I just changed a used guitar I got recently. It was nasty. You know when you feel crud on the back of the strings. The fretboard was bad too. So anyway how often do you guys change strings and why?