[tongzilla]

Assuming the ball is positioned before the clubface reaches low point and assuming an On Plane Swing :

a) if the clubface is square at Low Point, the clubface will be sightly open at Impact and you will strike the inside aft quadrant;

b) if the clubface is very slightly closed at Low Point, it will still strike the ball on the inside aft quadrant;

c) if the face is closed quite a lot at Low Point, the clubface will not strike the inside aft quadrant [and you will get a great big pull!].
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rwh

But the crucial point is that at Impact (not Low Point or Separation), the clubface must be open to strike the ball on the inside-aft quadrant. Even if the clubface is very slightly closed at Impact, it won't contact the ball on the inside-aft quadrant.