Shotguns. If it gets wet. It gets cleaned
Handguns. The same. Or if I put quite a few rds down range. It gets a cleaning.
Rifles. Get to know how much fouling your guns like. With my rifles. Most like some fouling. If you take all the copper out. It always takes some shooting to shrink the groups back down. I never go on a hunt with a clean bore. Moving parts need a little lube tho. Don't get too carried away. Oil works as a dirt magnet. Situations vary.