I find using the circular process invaluable at some stages, specially for maintaining perspectives...by creating blocks of area, it helps with layout, and overall presentation on your medium...
For instance, with feet I ALWAYS layout with circles...for the toes, then for the ball of the foot, then for the heel...then I join them all together...Even in the higher end human form books I have, they use circles and blocks before laying in any details, so as to assist with perspectives and foreshortening and stature, etc...
I used to draw the upper layers of things (start a dog, draw a dog, no inbetween issues) however I have learned that an artist really needs to understand the LOWER layers in order to understand a subject...For instance, take Bateman (my fav), he has sketches he has done that are skeletons and then he fleshes them...just to understand WHY a shadow is in a specific area of the animal, and understand HOW to create the upper layers based upon the way an animal was crouching, jumping, sleeping etc...
I personally think its very important that the artist needs to understand the lower layers of a subject in order to present the upper layer...
I now step off my soapbox...