I still am not 100 percent clear on hook face but I do know it is an unalterable result of the clubshaft attachment angle and the club heads weight distribution based on the geometry of the club face and loft and each club has it's own degree of hook face throughout except maybe the putter in order to give the club it's proper relation to the plane line referring to the down and out impact. It seems the 4th edition mentions the bit about attachment angle and weight distribution but not the 5th or 6th. Also The clubs "squared awaay" position is not always an indicator of it's actual position. The clubs leading edge may be square (perpendicular) to the target but when you put a pointer on the face, it may point slightly to the left showing it's true position, most wedges will show this easily although the Dave pelz wedges seem to point straight according with their leading edge. This is the minutia involved and required for ultra precision which is not always feasible or required to play great golf.
I have worked very hard on getting balanced making a proper pivot as homer tells us zone 1 is so important for good golf. This year I'm gonna continue to perfect the pivot and start getting more detailed in zones 2 and 3. Although I have a ton to work on upon re-viewing the hybrid swing FO I would argue that I'm executing a dual horizontal hinge cleanly.