Grampa got me started shooting when I was about 12 years old. He told me I could never 'over-clean' a rifle or shotgun. Then when I was on the base rifle team in the service, that teaching was reinforced. Consequently like Daveboone I clean 'em after every shooting and periodically throughout the year.
Oh, and I only have 1 rifle, muzzleloader, and pistol. Why you might ask?
"Beware of the man with only one gun... for he knows how to shoot it."