[O.B.Left]

I've been talking about hand paths in the context of the Turned Shoulder Plane because it's the most common, but let's look at the Turning SP - the version with vertical moving arms. Homer says the hands trace a line on the ground INSIDE the base line, so in this case, the hand path NEVER lies in the Swing Plane, unlike the Turned SP in which the hands trace the baseline from the Top.

Or you could also see it as a constantly shifting plane. Up Up Up on the backswing and then WAY DOWN , "vertical drop " so to speak going the other way. Furyk style .
This was a popular procedure back in Homers day the era of "sky high hands" and covering the Base Line with lots of "extension" in startup. I used to do this . Homer called it Steering , but so long as the golfers returns to the ball in a manner consistent with 3 Dimensional Impact Alignments the ball does not know the difference and so he himself would teach the Turning Shoulder Plane to those who for what he termed "psychological reasons" just couldnt stop swinging like that... it was after all very common back then . Normally with a reverse C finish and lots of knee drive. Homer wouldnt fight it for too long , he would just improve it (vertical drop I imagine being a common improvement) as he reasoned the "game is supposed to be fun". Now if you had a more ambitious student ... that might be a different story.

BTW Furyk's dad when teaching young Jim the game placed a wooden ruler behind the ball and encouraged him to cover it on the way back. Thereby taking him off the elbow or shaft plane immediately and shifting his plane angle up up up continuously . Its more complicated mechanically than is necessary but assuming you can ingrain consistency it is just as effective in terms of impact dynamics.

Some folks would point to Furyk and say " Where's your plane angle now , Homer!". But the geometry is still there if you know where to look.

Homer might not have been perfect but he was a bleepin genius IMO.