[Max Impact]

The D Plane assumes that the Ball Rolls on the Clubface. Impact and separation points are always different and D Plane never assumes Max Compression.

All Hinges produce a sustained line of compression, so all hinges give maximum compression. The Angled Hinge tilts the Line of Compression.

The D Plane is a term for the plane connecting two impact vectors. It is not an analytical model. Hence, The D Plane doesn't "assume" anything.

The book clearly identifies only Horizontal Hinge Action as the ideal application of linear force, producing perfect vector alignments.

And for the record, an arched left wrist, or its equivalent, would produce more compression than The Flat Left Wrist, or its equivalent. This would, of course, "hood" the clubface, which the book suggests to avoid. Although, virtually all great ball-strikers do it.