In my experience, you can do more damage to a bore/crown by cleaning it than by shooting it.
I don't clean my rifles very often, I wipe them down any time they've been out in the weather/rain/dust etc. I clean them at the end of a hunt.
In my experience, it takes a few rounds to get them fouled correctly to REALLY settle down, I don't want to waste the barrel on fouling shots
When I do clean one of my barrels, I REALLY clean it.