Light is what we receive, light is what is given off, light is what we see, light is what we understand...So why is it we have to draw in reverse, we draw darkness. First you have to learn to see values of color, then draw everywhere where those values are minimum. I'd think that if you were to draw on a black paper with a white pencil you would end up drawing better faster. Learning to draw well is difficult because you are trying to get at least 10 different skills/factors right at one time. It is like trying to guess a 10 digit password right and It is easier to guess digits correctly one by one than the whole. Drawing in reverse order is one of factors and obstacle-like thing to understand and overcome, shouldn't we progress to that later if we must.
I am asking here for the opinion of others in this general field of art/graphic design/etc.