Let me preface by saying I'm a benchrest shooter and generally very particular about keeping my bore's perfect.
Boresnakes, properly used, are a gift from the gods of shooting. They don't do a perfect 100% clean job, that's not their purpose. What they do is let you quickly and easily get about 95% of the job done, which is more than enough for the vast majority of cleanings done. If I'm cleaning one of my benchrest guns I start with one and move on from there, but why would I waste ten minutes when I could do the same job in ten seconds? If I'm cleaning a 10/22 or one of my defensive handguns or a hunting rifle... I soak/spray... the area ahead of the brush and the brush area itself with whatever cleaner I use on that gun. For general purpose that used to be Breakfree CLP, then due to the scent bugging my gf I've started using bore eliminator and slip2k clp depending on the gun. Then I run it through once or twice and take a look. On the 10/22 that's often all I do for the bore since I use the CLP products on it. I've run regular patches through it afterward a time or two, and gotten nothing but oil out as long as the boresnake wasn't used too many times between cleanings.
On a more finicky rifle I start the same way and then run a soaked patch with solvent through and let it sit a bit, then a soaked brush for a few trips, generally nylon but my larger bore hunting rifles that are less precise but also tend to get more fouling get copper brushes. Then another patch with cleaner and then some dry ones to clear things out. I won't bore you with the rest, you get the idea. But the key here is that even on my very old, very cherished very very precise 222 remington I can run that boresnake through and probably skip most of the rest and get the same result. It's more for me than the gun. Generally, unless I put a LOT of rounds down range I get nothing else from the bore after the boresnake and the first solvent/patch run. The brush tends to be purely a habit, and I've noticed that unless I use a brand new nylon one I wind up actually putting more dirt in than I free up.
Boresnakes aren't a replacement, but I'd be willing to bet that used right you can substitute them for traditional cleaning far more than most people think. My 10/22 and now my M&P are test cases for me. They're going to get very few and very minor traditional bore cleanings. A swipe or two with the snake and then a patch through to check and that's it unless the patch comes out dirty at which point obviously the boresnake has failed the test in that rifle, I'm curious to see what the threshold is. So far, with the 10/22, lead or copper jacketed doesn't seem to matter. Nor how many rounds fired. I've done everything from 50 rounds to five hundred rounds in a session and it always comes out spotless with two passes. Maybe the higher velocity of the 5.56 will change that, but I'm willing to bet it doesn't make much difference. The round count might, so maybe if someone else is paying for ammo I can try putting as many as a thousand rounds through it before cleaning the bore. I honestly don't know how that would come out and am interested to find out. I'm not about to stop my more careful and anal cleanings on the precision rifles, but I know that my time spent cleaning it got cut drastically when I started using the snake first.