Well by hand, using SMR shouldn't use all that much product. Remember that only so much polish can contact the paint at any one time. It's hard to describe, but I try to use enough to get a thin but even "coat" of product on the area I'm polishing. I don't really know much about "dusting", but I just stop when the polish is starting to dry out and vanish, but not totally dry because it's bad to do any dry rubbing. The size of the area doesn't really matter - just do whatever's comfortable, but not too big. Personally, 2x2 is a bit larger than I'd do myself. Do one area until you're happy, stop and buff it off, then move on to the next area. At least, that's what I did when I was polishing by hand...
With IHG, you may want to try searching for some techniques on using it, as I've heard it can be picky. Since it's just a glaze though, I imagine you'd be using even less of it since it's just something you lay on the paint in a thin coat to add gloss.