i clean my mak90, aka asianthug47, every time i use it. i even clean it when i just don't feel like driving 2 hours to the range to shoot, so i just take it apart and clean it. i also play with it everyday after work.
my belief is a that a clean gun is nicer to have than a dirty gun. in addition, i love and respect this gun too much to let it look like a taliban's second-hand gun.
i usually run a patch with 3 drops of oil before driving 2 hours back home. after 3 trips with the patch, i put 7 drops of oil down the barrel. the purpose is to loosen the powder residue to make the cleaning easier when i am finally home. i may not clean it the same night, so it is nice to have some protection in the mean time.
i think the gun will be just fine if i don't clean it. i also think it is almost impossible to shoot the gun out of commission. even with no rifling left, ak47 will still serve its purpose of CQB. i just clean my gun because i like doing it.