One day I really got into this subject and came to my conclusion of it seems to not matter, unless, its recommended by the manufacturer. I thought it was weird I've never seen significant huge sections in instruction manuals on how to break in your barrel. However, I do always clean a brand new barrel and chamber to make sure to get any crud left behind from manufacturing. A light oiling afterward to make sure there will be no rusting issues and I'm good to go. What I've told customers over the years when it comes to breaking in do what you feel is right. You won't harm the barrel in any way by stringing your shot with one shot, clean. Two shot clean, three shots, clean and so on (unless you're careless with your cleaning rod and methods). One thing I try and avoid is to get the barrel overly hot; once I can't put my hand comfortably on the barrel for more than 3-5 seconds (as close as I can get to the chamber), I let it cool. Not based on much fact other than personal preference.
Just to be clear, I'm not stating my way is the correct way, its just my opinion and I havn't had any issues with any of my rifles.