[Daryl]

We may be beating Daffy Duck to Deaf or Death, but where in the book does it say Hinge Action requires #3?

There's not much more I can add to be more clear. I bolded parts.

2-G. The Physics of Hinging is, that, Hitting or Swinging, “Roll” is actually imparted by the turning torso and/or the orbiting Arms per 2-K#4 and 2-K#5 as described in 10-18. Practice these motions first with open Hands cause of the Flat Left Wrist, must always travel at the same RPM as the Arms and reproduce the Hinging inherent in the selected Lag Loading procedure (10-19) per 4-D, 9-2 and 9-3, regardless of Clubhead Extension velocity. See 2-P and 7-18.

...........The KEY to this Rhythm is the #3 Accumulator (6-B-3-0). As part of the above drill, hold the 45 degree Arm position while rotating the Hands and the #3 Accumulator through the three Hinging positions, over and over until you see that each position changes the LOCATION of the Clubhead. The Point to note here is that with each Hinge Action the #3 Accumulator has a different “In Line” motion – Dual Horizontal Hinging having the longest travel and Dual Vertical the shortest. This agrees with the “Roll Characteristics” discussed in 7-10 and must be so executed to produce proper Rhythm. Doing the above drill with Zero Accumulator #3 (6-B-3-B) will show that then, all Lag Loading and Hinge Action have Angled Hinging Travel AND Rhythm. So – intentional use of Zero Accumulator #3 can be useful while unintentional use can be hazardous.