Left arm and shaft should not be in a straight line. Take another look at the picture of Brian Gay, which I believe to be YODA's ideal.
Think of zero shift as a "feel" not a mechanically perfect requirement. I hope you don't mind me continuing to use pictures of Brian, but I think they are the model. These are pretty good depictions of a very slight shift in planes that would "feel" to me as zero shifting.
Kevin
great pictures there....BG makes an ever so slight shift to the turned shoulder plane, right?
It seems to me to be a very simple procedure to setup right forearm on plane as he has and swing around that plane line as Mo Norman did. The process of shifting would be mostly eliminated and then you just trace the target base line.....sounds like a new pattern for me to play around with