Hands have always been hard for me; even before I started to draw anime. I'd just draw what my friends called "little sausages on a circle" and be done with it. Your Hand Studies have given me a lot of help :3
Oh! Tip on the "Fingers begin roughly where thumb ends": If you put your hands out like that, and press your thumb to the side of your index finger (Just put your hand how the pic shows LOL), the last knuckle on your thumb should roughly align with the first knuckle of your pinkie.
You motivated me to try drawing hands for the first time! [link] I also tried shading for the first time, I think they looked better before I did that, but whatever, I hope I improve. You're submissions like this are really useful!