Sometimes I would spend 2-3 hours cleaning and other times 4 hours or more cleaning.
I now reduced my cleaning to just an hour and a half. I got this process down pretty consistent since about 2 years ago now and can safely endorse it. What I do is use Boretech eliminator on everywhere. I put the solvent on a patch and simply use their pick to swab it everywhere. I use a nylon brush and whatnot to get it scrubbing with the solvent. After doing this about 2-3 times over with a wet patch and scrubbing at all the wear points and carbon areas (inside bolt carriers, inside the rails of a pistol, bolt face, slide face, inside the upper receiver, etc) I would blast it down with gun scrubber. Then I would apply my clp-ish product. I would never use it in places that don't have carbon buildup though, like the lower or anywhere external.
I can show you a situation where I take a clean patch and you cannot see one black spot anywhere on the bcg inside or out. I can spin it 360 inside the carrier and not a single black spot.
But yeah this boretech stuff cuts down. Don't let the word "bore" truck you to only using it in the bore.
The one slip product that I really wanted to work was their carbon cleaner tub thing. I really like the idea of putting a bcg into that green liquid and let it soak in. I had mixed success with it but it does seem to work. I also bought the quart size thing (I think that's what it was but a bigger bottle of that green carbon killer thing) and it worked pretty good I think but never could get the process down with it and again spent 3-4 hours letting that thing soak and cleaning it and letting it soak, and cleaning it, etc. Never consistent with it but sometimes I would have a "ah-ha" moment where it comes out spotlessly clean.