...and being pragmatic...may i ask, bottom line, what does it matter?
Is it that you cannot 'lean' on the spiral line across the body? What is the worst mistake you'd make with this assumption?
I have no idea what relevance "leaning on a spiral line" has to do with this... that one you own.
In terms of mistakes, where to start? There are too many. Ultimately, you have to start modifying an "X" in order to account for some of the things that functionally arise or to explain some of the more sophisticated methods of developing power. But maybe Dan has a more sophisticated explanation of his "X" figure.