I have been shooting small bore prone for the last three years and this is a topic of interest.
Competition rifles are cleaned from the breech and use a bore guide. When they are cleaned, the interval between cleaning can be a very long time.
I have had experienced competitors, guys who have won the big matches at Camp Perry tell me that they only clean “when the barrel tells them to”. This is by evidence of poor shots unexplained by wind, hold, or trigger pull. I did not get a good answer about how many shots it takes for a barrel to be talking to its owner, but it has to be thousands or rounds, not hundreds of rounds. You shoot almost 200 rounds per small bore prone match. Incidentally these guys shoot at least once a month, usually more. The fouling does not get a lot of time to age.
Incidentally, one competitor told me he had fired at least 700,000 rounds through his match rifle barrel! (I did not ask how often he cleaned it)
Every competitor I have talked with, and I have seen this myself, will tell you it takes a couple of fouler shots out of a clean barrel to stabilize the group. And this is also try for different brands of rimfire ammunition as the lube is different between makers.
I asked Ten-Ring Service (706-647-5941), who were on Commercial Row fixing competitors rifles, about cleaning a match tube. Their advice was long and I don’t remember all the particulars. But they said use powder solvent first, patch the barrel dry, , and then use a dry bristle brush at least ten times to mechanically remove any leading that might have collected in the nooks and crannies. Somewhere at the end you patch again. I don’t remember if they said it, but most cleaning advice on match tubes comes with disclaimers about not letting the rod or jag touch the crown, throat, anything.
I believe and I have seen recent articles on this, sharp edges from jags, rods, will scratch and damage the crown, bore, and throat, so for people who don’t have bore guides, it would be better not to clean their rim fire barrel.
However, I have lived in areas of high humidity and have examined 22 LR barrels that rusted internally because they were not cleaned. So if you live in one of those places and it is months between shooting sessions, you have to take that into consideration when deciding to clean your barrel.
If I'm not shooting, I'm reloading.