I haven't really played one guitar long enough to know when I should refret. But, I have the very first guitar I got...the one that I played for 6 hours everyday for about 7 years. I put it away for a few years after the bridge pickup went dead, and a few years later I bought some EMGs to put in it. A year later I ran into some financial problems, sold the EMGs, and put the guitar away again. I just got it out last night and was looking at it, and the first few frets have divots in them where the strings are, and the higher frets (12-17)are flat from playing leads. The really high frets are still round. The last I knew it still played fine. When does refretting become a neccesity?