Visualising in 3D vs. memorising lines - Part 2

A member on the Sweatdrop forums was asking how to draw the head from a low-angle view. I drew two examples of how I tend to approach this particular pose.


The example to the left keeps the normal, frontal-shot face shape. The only thing that happens is that the facial features are shifted upwards so that the chin becomes larger, and the underside of the nose becomes more prominent. The second example illustrates the tilting of the jaw and tends to look more extreme than the previous method.
The first example is an approach which I was able to do from very early on, but it took a few years before I could use the second method.
I learnt the first method by copying other people's work without really understanding the underlying principles. The tilted jaw line was more difficult to reproduce by copying however, so I was only able to use it to good effect once I could visualise the 3D form of the head.

It would seem that the 3D approach is far superior than the line approach, but if we look more closely, the two may not be totally unrelated.
Someone able to draw a face/pose without guidelines might have learnt how to draw using the line memorising approach, but, it could also be that they're so used to drawing that face/pose that they've moved past the need to construct in 3D. They know what the form looks like from any angle because they have already worked out the 3D problem multiple times, so they can now jump straight to the solution - the lines.

So, what's the difference between memorising other people's line patterns versus working things out yourself and then, when you're comfortable enough, use the line patterns you've learnt?
I believe the main difference is called your personal style.

Visualising in 3D vs. memorising lines - Part 1
Related post: The art of copying