I think Edwards's approach is more compatible with Ames's construction approach than your description implies.  Sure, Edwards is trying to get you to see what is in front of you rather than rely on preconceptions.  But what is in front of you can often be described as a collection of generalized shapes, as Ames does.  And, indeed, this is a good way to get the initial proportions of a drawing correct; I believe Edwards discusses some helpful construction rules in the portrait section of her book.<p>In other words, you should draw a circle not because someone told you to draw a circle, but because the thing in front of you genuinely has an underlying circular form at that size and in that position -- as Ames must have done when he came up with his drawing books in the first place.  And the more you do this, the faster you learn the underlying structure of things, which makes it easier to draw from memory, draw from imagination, or simply draw from life without needing to stop as frequently to measure things.