[mp33]

Let's look at real world evidence. Most pros have the leading edge either "square" or slightly "open" at the Top, because most have a neutral grip with a Flat or slightly Bent Left Wrist at the Top. Amateurs have it all over the place.

I agree with you that amateurs have it all over the place.Does the flat left wrist fix this fault or is that too simplistic?

I'm not a teacher but I see this all the time with higher handicap players and how would you go about fixing it?