Ethical range is different for different folks. Some one that only shoots 25 shots a year, range is shorter than some one that shoots a thousand or more shots a year.
Also a clean or fowled bore can depend on the gun it's self. I know how each and every one of my rifles and shot gins react to a dirty or clean bore.
A 7mm08 I own is the only one that needs a dirty bore as the first shot from a clean bore is a flyer. all the others like a squeaky clean bore. So range time isn't just for punching holes in paper at known yardages. A note book with how a rifle or shot gun(slugs) reacts to different conditions is a good idea.

Al