As Berty said every barrel is different. I sometimes think that the barrels need a small bit of lead in them to work better rather than super clean.
Both my AR5 and AR5s get a proper clean at the end of the summer but other wise it gets a pull through every other month with a patch that has a small bit of barrel cleaner on it to slightly clean it.
My Rapid I have only cleaned it once in the 10 years of ownership. Will give me groups of 3/4" at 45yds with a full magazine rested (.177 cal) which I am happy with for HFT and Hunting when needed.
A good friend owned a RN10 during the 98 GP season that had to be cleaned after every 3 weeks or so. He was using 7.9 Premier at the time as was shooting it every weekend getting through about a box and a half of them a month.