I clean my .22 match rifle every 100 rounds or so. First, in goes a cleaning rod guide replacing the bolt. Starting with two patches a little wet with Hoppe's No. 9 back and forth severa inches then out the muzzle. Next come the bronze bore brush; 10 to 15 round trip strokes the full length forward out the muzzle then backwards out the breech. Then 3 or 4 more patches damp with Hoppe's followed by 2 or 3 clean patches.
And yes, squeaky clean rimfire bores need to be fouled with a few shots 'cause they shoot high at the beginning. Bullets leave faster and they need to be slowed down by lead and powder fouling to just the right amount. Then they'll drive tacks for about a hundred shots.