[Yoda]

I don't have the answer, but I am curious to know why hitters have to adopt a cross line procedure and hence use a 10-5-E.

Anyone with answers?

Hitters and Swingers alike can use the true Geometric Plane Line (the Baseline of the Inclined Plane). Being the 'Basic Basic', it can always substitute for either of its Visual Equivalents, i.e., the Swinger's Arc of Approach and the Hitter's Angle of Approach.

Just be aware that the Right Arm's Drive through Impact is a linear motion that will tend to take the Club above Plane during the Follow-Through. If you need a Delivery Line to help guide this motion, then it's time to adopt the Closed Plane Line of 10-5-E. Remember, though, that you don't Trace -- point at -- this Line with the Clubhead. Instead, you cover it.