I'll agree up there that phew things suck more than having down an almost finished sketch, only to realize that the most awesome hand you've ever drawn to date just happens to be slightly larger/smaller/farther than it should be. Then you enter rage mode trying to determine what to do.
I may have ended up erasing everything but the hand and redoing the rest a few times in the past xP
Though, if just sketching for sketching's sake, there's no need to get accurate. Though, it is my feeling that the more you practice, the more natural such precision comes.
My main nemesis is human feet. Inevitably, I make them too big. * sighs *
If I were doing something more serious, I would have put a lot more thought and effort into laying everything out beforehand. But this was just a quick thing that was like "Aha!" so I just went with the first sketch that seemed good enough. XD
She was supposed to look more concentrated, but yeah, they do look smug. Oh well.
I think a better workflow would be to sketch out all of your elements to make sure your composition is all set though. It would suck if we find that we misplaced a hoof or something then you have to redraw parts again.
So people say, but at least in this case, there really wasn't much more in my head than that image. I really don't know what's going to go on with the rest, so I'll probably have to redo some things, but I don't mind that too much. I like the process.