I clean my weapons after every use. Learned it from my dad. Same principle applied to using the family car (if you don't wand to wash and wax it, you don;t need to drive it). Works for me.
I had a mossberg 500 tactical that I traded for a Maadi AK. I miss it. It was scratched to HELL. Dirty and grungy. "but she's in good shape for the shape she's in. Cause she's been through the fire before and i reckon she could take a whole lot more". We shot so many different kinds of shells in all types of conditions through thy thing.
I use a touch up bluing pen and a flat black paint pen to hide any bad bangs. I ignore magwell scrapes, for example my P226 looks like a rat lives inside the magwell. The finish on my M&P15 (I guess the Troy TRX is what gets beat up the most though) has been holding up surprisingly well. I do have little silver lines all over it from it rubbing on my aluminum cobra buckle. The lines come off but they can be a pain so I just stopped trying. I think my weapon light takes more of a beating than any other part of the rifle, rail included.
I see a bunch of posts about cleaning regularly. Regular cleaning wont help your weapons finish when you hit the dirt hard, say into urban prone for example, and the weapon bounces off the ground.