Russ, I agree that the new strings don't keep sounding new for long, and as long as I can tune the strings, I'm really OK with keeping the old ones on.

But I hate having to change a string during a performance, and I can't count on my roadies to hand me another, tuned guitar when a string breaks.   (That may have something to do with the fact that I can't afford any roadies.) So if I have an important gig coming up and I haven't changed my strings in a few months, I may change the strings (keeping the old ones as back up) just to be on the safe side.

Yes, I've had a new string break shortly after I put it on, but it doesn't happen often.