I'm with handofcod on this.
There are very capable BR shooters who will disagree, and they get good results, but I've seen no evidence that it measurably improves anything.
If it were the case it would be very simple for someone to take two of the same rifles and break one in, not break in the other and show the results with the broken in rifle performing better. I've never seen such a test and of the millions of shooters out there someone would have done it if this was the case.
1,000 people would have done it by now.
People take an new rifle, follow their chosen break in process, find the rifle shoots well and credit breaking it in for the accuracy. A comparison of 1 is no comparison at all.
I've sold my previous rifles and just use my Tikka sporter now. This is the first 4 shots from it.
And it still shoots the same hundreds of rounds later. Putting 100 round through it first in increments of 1 or 5 or 10 or whatever someone says would have just been a waste of 100 rounds and hours of my time.
If anyone has anything more than anecdotes which suggest the contrary I'm all ears.