I see the Hogan arch at impact as a product of his shaft lean combined with his left hand grip type......weak. Its also a "never gunna pull or draw, never go'n left, no sir" clubface management thing.

I say that his Arched Left Wrist at Release allows his shaft to lean with His Weak Grip, and his weak grip, Vertical at Impact, slows the rate of Closing and Layback making a Hook or Draw almost impossible.

No doubt in my mind that Hogan used a Simultaneous release as a standard although he sequenced his release occasionally. He was versatile.

Basic questions about "bending the plane"
 

I have MANY questions and comments but I will start one at a time:
Considering the following: For swinging,
2-F. "The right forearm of every Hacker comes into impact too high."
Trace the plane line.
The RFFW -needs to be maintained and laying on the plane.
The full pivot stroke contains the basic motion.
Impact fix still retains #2 and #3 accululator "action"
As I understand it- #2 is triggered first because the shaft is on the plane and #2 continues to be released until end #3 exists as long as some #2 remains but #3 can not trigger until left hand starts to be rotated to vertical then with precision #2 and #3 work together to keep th shaft on plane too impact , low point, end.
Now -- how can this be accomplished other than on an elbow plane?