If stored in a dry environment, most firearms need little "cleaning" until they start to show accuracy or functional degredation. Modern ammo deposits very little residue that is not likely to cause rust unless subjected to high levels of moisture. Oddly, the only rifle I've had show bore "rust" ijn a long time was a 17 rimfire that uses jacketed bullets so produces very little residue. I have no idea why since it had not been exposed to moisture any more than the other rifles sitting beside it and had not been fired for months.
I try to pull all the firearms out at least once a year and run a patch dampened with Kroil through the bore and wipe exposed metal.