Cleaning bbls

Clean it once you see accuracy degrade. If you subscribe to the SH Online Training, Lowlight has a great video on cleaning. Give your rifle a really good, thorough cleaning and then note your accuracy. Shoot it until you start seeing groups open up, then you'll know at what point you need to clean it. I've heard of guys needing to clean every 100 rounds, some rarely clean their rifles,

Personally, I start to get the "cleaning itch" after about 250 rounds. I will wipe down the bolt if I get a bunch of sand/mud/etc in it, but I leave the barrel untouched for at least a couple hundred rounds.
 
I never clean my rifle at a match. It takes several rounds for it to settle down (especially vertical) after a cleaning, and that will kill you in a competition. I think the advice given above is the best solution. Just clean when accuracy starts to degrade. FWIW, Mid Thompkins told a friend of mine that he cleans his bbl at the end of the season. On the other hand, some guys clean the hell out of their bbls every chance they get, and they shoot well. Who knows???