So, I learned something fairly useful while modelling the hand: Maya's split polygon tool is shit. Both the newer 'interactive' one and the older one. They're both complete trash. I didn't realize it before, I think, because I was still too intimidated by Maya to question it on things, but that fleeting innocence has passed and I am now fully aware of just how dumb and counter-intuitive those tools really are.
I also learned that there exist much better ways of sculpting geometry within Maya (and, duh, of course there's been better tools this whole time, I just hadn't dug deep enough). It turns out that Cut Faces is awesome. Selecting face(s) and cutting them along an arbitrary plane in space, trough as many faces as I want,simultaneously, is so much more productive than playing connect-the-dots.
The other amazingly useful thing I discovered was the potential depth of the right-click menu. Turns out if you hold SHIFT when you right-click, you're given a much more specific menu, tailored to whatever tool and selection mode you happen to be in at the time. It was through this discovery that I learned about Merge Vertices and Connect Components. Those two, combined with Cut Faces, meant that I pretty much did the hand my own way, and ignored the practical documentation altogether...
Well, not altogether. The thumb rotation part was useful, and was certainly a bit tricky to get looking human-like.
(the Extrude tool is still my buddy. It still gets a Christmas card.)