I have a Guild D55, (1973, nearly thirty years), which I play every day, and have not had it refretted, although it is getting to the stage where I'm thinking about it. I rarely break strings, either, and I play fairly hard and sometimes with fingerpicks, though never with a plectrum. It also sounds heavenly, particularly with new strings but I only change those every 2 to 3 months! One of the things I take particular care with is making sure there are no sharp edges on either the nut or particularly the saddle where the strings run over them. I also use a trace of lubricant in the grooves of the nut to allow the strings to move smoothly as they are tuned or detuned . And wipe the strings with a smooth cloth after use!