Wow! So many different approaches. If I'm after maximum accuracy, I clean the bore after about 15 rounds. Yes, many folks, including me are thinking that you need some amount of copper in the bore. How much copper is the tough question, and I think it varies with the rifle barrel. This is something you need to determine with your specific rifle.
I spent the last two days shooting my 220 Swift and I laid down a lot of copper. From the patches, cleaning with Boretech Eliminator, I think I could have made a copper bracelet. Hoping to start from zero copper, I cleaned the rifle and shot a fouler or two and then some groups, and the old rifle shot great. I have a rifle or two that want more copper in the bore than that.
As for cleaning, I'm a Boretech Eliminator fan. That stuff will clean out the copper. First I do a light cleaning of the bore with Butch's Bore Shine to get the carbon fouling and some of the copper. On some rifles, that's where I stop. On other rifles, I'll work em over with the Boretech to get most of the copper. As for the Butch's Bore Shine and how good that is, I think I slightly prefer Shooter's Choice, but I have a big bottle of Butch's to use up.