Some prefer to shoot until precision begins to degrade before cleaning the barrel. The problems with this approach are that you cannot know exactly when this will happen, and that when carbon and copper fouling are left in the barrel for an extended period, they are that much harder to completely remove. In fact, once carbon deposits acquire a shiny "black volcanic glass" appearance, they may be almost impossible to remove without using treatment with abrasives.
The converse to this would be cleaning too often, something I believe is not really possible to do. But for the sake of argument and covering both sides, over-cleaning has been proposed to unnecessarily decrease barrel life, in addition to requiring time/effort. Again, I do not believe that a proper cleaning regimen will ever harm a barrel, or decrease its useful life. Nonetheless, those that are of the mind that cleaning only when precision starts to fall off is the correct approach often use this argument in favor of cleaning less often.
I personally clean a barrel whenever it has been fired, regardless of whether that is one round, or 100 rounds. One key to cleaning every time a barrel is fired is that you will want to know how many fouling rounds will be required with the clean barrel for it to obtain "full" precision. The only way to know that with certainty is to test it. I predominantly use Bartlein 5R barrels on my F-TR competition rifles. Via routine testing, I know that my rifles will be up to the expected average velocity for a given load within 3 shots. "Full" precision is a little more difficult to gauge, as it can only be done by shooting groups. For that reason, I typically like to put at least 5-6 fouling/sighting shots downrange at the beginning of a match, practice, or load development session. The other coincident issue with regard to fully fouling and bringing a barrel up to "full" precision is that the shooter themself also needs to be up to "full" precision. Again, that is something that will vary from shooter to shooter, but is something that can be observed and recorded at almost any shooting session. How many shots the rifle needs to get up to speed and how many shots the shooter needs to get dialed in may not be the same number, but reliable numbers for each variable can readily be determined from a few range trips.