1Shotking to answer your question YES.
What I found on my very non scientific break in was it made no difference in accuracy when all was said and done.
I followed the recommended procedure more than once and then on a few others just shot then cleaned when I got home then did the same a few more times,and basicily these guns perform the same, they clean up the same(when I clean), no different.
I read once that a barrel maker said that the procedure was to get you to shoot your barrel out quicker,hence needing more barrels leading to more sales.Google "barrel break in" you will find it.