Kinda like that, though I didn't pick it up there (I picked it up from several art books and some other sketches I've seen). Dunno when I exactly started doing it but since I did, I honestly cannot draw a human head without the circle now and I draw waaaay too hard to erase it half to the time, so alot of my sketches end up getting it left in there. I guess it just basically makes sure the hair is high enough on the head and everything is proportional. So I guess basically I draw EVERY HUMAN CHARACTER I draw bald and then sketch the hair on top of it (can you tell I depend on Photoshop and layers too much heh).
You're -supposed- to do that for the whole body but more often than not I just free style the rest.
Oh and all the black scratchy things, the floating little girl in the decorated robe, and the bald guy with the beard are all from a series I wrote the beginning to long before starting TCS. I've considered making it a story based serious comic several times, but its mostly just a idea in the back of my head I enjoy sketching.