> But does anybody really understand all of the levels?

Of the top of my head? Most of them. Did you need me to understand some level in particular? I can dedicate time to that if you like. My experience and education will make that a very simple task.

The better question is.. is there any _advantage_ to understanding "all the levels?" If not, then what outcome did you actually expect? A lot of this work is done in exchange for money and not out personal pride or desirous craftsmanship.

You can try to be the "Wizard of Oz" if you want. The problem is anyone can do that job. It's not particularly interesting is it?