Interesting, Tom - concerning breakin- good or not worth while. It's kind of like the scenario of brush or don't brush - there are champions on both sides - kind of like what makes a good deer rifle and what doesn't - exits or bullet remaining inside the animal.
As to brushing, I find all fouling is removed without brushing - maybe a bore scope would prove me wrong - don't know. I do like to fire 300 to 600 rounds without having to clean (BR shooters cringe at this) with velcoities in the AB and AH runing 3,900fps to 4,150fps.

As to cleaning back to steel after 5, 10 or 20 shots, eventually, the bore becomes 'broken in' as Curl notes.

Break-in with shoot/clean, shoot/clean with a hunting rifle? I couldn't be bottered and yet most of my hunting rifles will stay around or beneath 1/2MOA with good wind condtions. 30 years ago, with the bullets available then, this wasn't the case, yet with the norm of 1" or 1 1/2" they had enough available accuracy to consistantly kill deer, elk or moose at extended ranges - my limit is 300 - thankfully, haven't had to shoot that far - ever.

If your bore fouls excessively, the break-in noted by many here, shoot/clean back to steel, shoot/clean back to steel can be done at any time. It's just damned difficult to get back to steel if 10 or 50 shots have been fired without cleaning. The buildup of metal fouling requires long sessions with solvents, brush and patches & this 'heavy' cleaning, I feel, is where many crowns and chamber thraots are worn due to the use of commercial chamber guides or non-use of guides altogether.

A guide that stops at the the chamber mouth (case head area) merely gives the illusion of protecting the chamber. The throat is the area that needs to be protected, not the chamber's mouth(although a groove there isn't good). I build my own guides for each rifle that sees a lot of ammo, using a case that fits the chamber and chamber's neck.

Wipe Out has made most of these redundant as a quick spray, left to sit overnight, muzzle slightly down, then a patch through in the morning leaves a clean bore, yet not finished. I now run a patch with kroil or other oil bearning solvent through the bore, then patch that out with 2 sticker patches that fall off at the muzzle. NOW the barrel is ready for storage or for shooting.

One rifle bore of mine needed 2 nights of soaking with Wipe-Out to get all the guilding metal out - a 1929 Husky 9.3x57 with a 'good' bore. It's perfectly clean now, but still fouls easily, yet the accuracy remains the same, fouled or clean - never changing - always under 1" with any bullet weight from 232gr. to 300gr. - What a rifle!