It depends on your rifles chamber/throat diameter compared to your bore groove diameter how long you might go without the carbon ring causing degradation of accuracy. Once the carbon ring builds up to where it squeezes the bullet smaller than your rifle groove diameter you loose accuracy. There is insufficient pressure in a 22LR to obturate the bullet once squeezed down. Most benchrest rifles are built such that you need to clean the carbon ring fairly frequent. Soaking a bore mop with C4 and letting it sit is probably the smart solution to carbon ring. I have impatiently used Isso and other mild abrasives but eventually the minute amount of wear adds up and putting a mirror finish in the throat may not be best.