I generally don't break in barrels by the one-shot/clean method anymore. And yes, I have worn out a few barrels.
With custom hand-lapped barrels I may fire a few bullets (maybe 5) with a mild abrasive just to smooth out the tool-marks in the throat, which should be the only tool-marks in such a barrel. Or I may not, if it shoots really well from the beginning.
With a factory barrel I may do the same, but if it looks like it's going to be a real fouler I do the Ultra Bore Coat thing. It's a lot easier than one-shot/clean, and usually the bore ends up being significantly more foul-free.
