Not an expert here on this subject, but I will tell you that I have a NOTICEABLE difference in my 50 and 100 yard groups with my Omega 50 cal muzzleloader (stainless barrel) after shooting 80 rounds through it and cleaning after each shot. The group at 100 yds went from 4-5" down to 1-2" and this happened somewhere between 50-75 shots.
The other thing I've read about breaking in barrels "the right way" is that if you take your time and do it right, it's like the difference between heat treating metal slowly or quickly. One way you get superior steel over the other. Hastening or shortcutting the breakin process will yield an inferior metal that has larger "pores" in it which will collect more copper and foul quicker than had the break in been done "the right way" (clean bore after every shot).
I will say this from experience with some metals in my line of work; Each of the satellites we build requires a hub of machined metal at the bottom (approx. 16" high) that we attach with a band to the top of a rocket booster. This ring of metal is machined from a solid forging. 90% of the mass is machined away. One thing we've learned in doing this; you cannot accelerate the process of aging the metal between machinings without creating problems. One of our vendors tried to artificially age the material (heat it up, cool it down over and over vs. waiting at ambient temp for a period of time) to speed up the 4-6 month machining process. The metal kept "moving" after and between machinings. So, they had to go back to the tried and trued natural aging method, nothing else we could do. Physics are physics and metal acts the way it does with heat and cold over time according to laws of physics, not our wishes or trying to force those laws. Just a thought, maybe the "right way" to do something (breaking a barrel in) is the hard way, but also the best way for proven results.....