My cleaning routine and reality are from the short range benchrest perspective. Within that, there are shooters that clean after every target, and those that go several between cleanings. I fall in the latter group, and made the change after a conversation with George Kelbly, over 15 years back.
Generally the fewer rounds between cleaning, the less effort required to clean. Also, barrels differ as to what they prefer. I have had barrels that seemed to shoot tighter as more rounds were fired, up to the point where I was not willing to risk going any further, this shooting 133. I have had others that did better clean. With 133, I have gotten satisfactory results by only brushing at the end of an aggregate, with a single cleaning with patches and solvent after the third target. When I have brushed, I have found it advisable to shoot more rounds on the sighter to settle the barrel, so as to avoid surprises on the record target. As I mentioned with that powder, it was not necessary to use an abrasive at all.
As far as JB or IOSSO not being abrasives, I will simply say that I disagree, they both clean with the use of particles through mechanical action, and the IOSSO has some chemical component as well ( I believe). Certainly they are not as severe in their action as lapping compounds, but particularly in the case of IOSSO, you can see some actual polishing action from its use. Neither one will scratch a barrel if properly used. (They both require some care as to rod guide use and selection, as well as rod technique, in order to keep from wearing crowns and throats.) Based on experience, IOSSO is more effective for hard carbon deposits that cannot be removed by brushing with a bronze brush and solvent. It is that particular class of fouling that I refer to as carbon, or what is generally referred to as "hard carbon". Anything else, to me, is simply powder fouling.
I agree that powder fouling tends to set up over time, and become harder to remove. All one needs to do to discover this is wipe off the neck of a freshly fired case, and let another set for a week and try the same thing. Smaller bores tend to be more finicky as to cleaning. I also believe that for some shooting sports were winning accuracy requirements are less, that cleaning less often can be better tolerated. This is not to say that these types of competition are less challenging, just that they have different requirements. There is also the problem as to whether the course of fire allows time for cleaning, or for fouling shots after it is done.
One last point, it seems that on the internet, much has been made about the advisability of only brushing from chamber to muzzle, and removing the brush after it exits the muzzle. I have never seen a short range benchrest shooter do this, and am not aware of any that do. This would include a number of current and past world record holders that I am personally acquainted with. I have also spoken with a number who have tried various nylon brushes for their ordinary, non abrasive, cleaning, and who came to the conclusion that they were not as effective as their bronze brethren.
As I stated earlier, the use of a bore scope is required to know what the inside of a barrel looks like both before and after cleaning. They are also very useful in determining how much effort, with what materials and tools are required to get the job done. They do have the disadvantage of sometimes causing shooters to become overly concerned with getting barrels absolutely spotless, which in my experience is not necessary, and which may do more harm than good, if done every cleaning. They can also lead to false conclusions as to whether a barrel has accuracy potential. There has been some fine shooting done with barrels that looked perfectly awful inside.
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