The cleaning depends on the gun some guys will shot 20-50 rounds before accuracy falls off some won't shoot 10 before accuracy drops , it all depends onm the barrel and how its treated. You can try to shoot several groups noting if they are opening up toward the last few. Typicaly I'd say for a factory gun ever 15-20 shots withg a 30-06 as it shoulden't foul as bad as a hotter mag. You just need to be sure that your getting all the copper out when you clean or you will eventualy get some build up.
As for the brass , Winchester is decient doens't seem as hard to me as Remington does. It realy depends on what your shooting , if you shooting you paps old factroy deer gun then I doubt you'll see a differance but if you have a well built factory gun of a custom that was put together right then I'd say buy some Lapua it'll run you about $.65 per case but it'll out last Rem or Win brass and is WAY more consistant, its the best stuff out their.
Another tip to keep you accuracy top side is to watch your reloading , change up primers and seating depths also you may want to invest in a Lee collet die , it'll make you brass last longer and they load some great accurate ammo.
