i cleaned my 223 service rifle once a year after camp perry whether it needed it or not. i'd guess it saw 2 matches per month average from march - august. matches were either 50 or 88 rounds.
my bolt guns... after barrel break in, i never clean. but that's because most barrels will shoot to a different point of impact after cleaning until fouled again and i'm shooting in practical/sniper type matches where i might not have an opportunity to clean between every during a 200-300 round competition. so i value consistency and 1st round hits. (we don't get sighters)
if i shot benchrest, i might scrub the crap out of it after every string. who knows?
like dale said, let the barrel tell you what to do. if groups start opening up and you know it's not you, then try cleaning it. if they magically shrink back to where they were, or if they don't... well, what have you learned?