[Yoda]

Why can't I find anyone who sets up on the turned shoulder plane
per 10-6-b #1???? The benefits would be a shiftless swing.

Photo 10-6-B #1 requires a "steeper-than-normal Elbow Plane" (7-23 / 6th edition) with a "reaching out of the arms" and a Left Hand Grip in the cup of the hand (instead of the normal under-the-heel of the hand). Or, an Uncocked (versus Level) Left Wrist. All of which borders on the "ungolf-like" (3-F-6).

All this can work well for the short shots and their steeper Planes. But, for the longer Strokes, a more normal On-Elbow-Plane Right Forearm at Address and the natural progression to the Turned Shoulder Plane in the Backstroke (Single Shift / 10-7-B) is more natural.

Stand in a Plane Board set to a Turned Shoulder Plane, and you will instantly understand.