So your forearms touch on the follow through ? That would be another way both
could be flat.
I don't see how both wrist holding the same shaft can be flat with a
conventional grip (palms facing each other). I just tried it with my trusty
dowel that now lives by the computer. You can reach a point where both are
only slighty bent, but as soon as you make one dead flat, the other one
bends.
When the Left Wrist is Flat -- whether Cocked, Uncocked
or Level -- and the Right Wrist is Bent and Level
-- no matter where Vertical, Turned or Rolled, that
would be...