As I have pointed out many times before, the one-shot-clean "break-in" procedure was developed by benchrest shooters who wanted their (very fine) barrels to be shooting their best before the first match. The technique accelerated the smoothing of (again) very fine barrels, because each shot was--supposedly--fired over bare steel.
If you just clean to bare steel every 10-20 shots (about how many rounds most of us shoot during range sessions) the same thing happens--at least with good barrels, With most factory barrels it makes little difference, because they're not as smooth as the very fine barrels benchrest competitors use.
