Think of it this way. You shot 15 to 20 rounds last weekend and didn't clean it. The next time you can shoot is a couple of weeks later, and you only fire a mag through it. Just a quick swab and into the locker/safe/closet. If you keep this pattern up you will forget how many rounds have been fired and when it was last thoroughly cleaned. Now you have a rifle with a buildup of grime, now it isn't fun to shoot any more because of FTE, FTF, and jams, as well as being able to hit what you are shooting at. And in the case of SHTF, your trusty rifle isn't any more.
Judging from the posts on this board, almost everyone is anal about cleaning their weapons after each shoot. Some prefer using bore snakes and similar, while others use the traditional method of bore brush and cleaner. But they all do a thorough job of cleaning at the first chance they get.
Your choice.