Shoulder Flow Symbols: Bidirectional Pictogram Layouts

Flow over the shoulder, goes both ways. Back to front on images A, B, C, F, H,I and K. Front to back on D, E, G, and L. Why?

I think the neck is in the way, and shoulder is the next best choice, when you want to show a flow loop-back over the top of the body-torus. I'm presuming the persons back is considered a side flow and the persons front is the center of the torus.

If nothing else, this at least shows common knowledge of layouts for pictograms across time and places.