Always big debate over words and happen with barrels.
If you look at Bartlein site and other custom barrel sites they all recommend something different.
I follow Bartlein advise from their site
"The age old question, "Breaking in the New Barrel". Opinions very a lot here, and this is a very subjective topic. For the most part, the only thing you are breaking in, is the throat area of the barrel. The nicer the finish that the Finish Reamer or Throating Reamer leaves, the faster the throat will break in."
I'm sure I can do without that step and I know some that skip it but takes me just couple rds so no big deal breaker.
In the factory rifles who knows. You have factory rifles that sell with test targets and when I use to buy Rem 40x that came with two 5 shot test groups I'm sure they didn't clean between shots.