[ronaaronson]

Homer selected to use ... the Turned Shoulder Plane.
First, why did he choose to do this?

According to 10-13-D, the right shoulder moving towards impact precisely on the preselected downstroke clubshaft plane establishes and supports the power package alignments -- the ideal way for the shoulder to move. But for the shoulder to move down the clubshaft plane during the downswing, it should already be on this plane at the start of the downswing, no? Well, the right shoulder will be on the downswing plane by definition when swinging the club on the turned shoulder plane. Zero Shift + Turned Shoulder Plane = Fewer Complications