That makes sense because starting out my pre-swing routine included the post impact swivel as in Lynn Blakes video. I hit some straight drives as far as I've ever hit but with far less exertion than before.
As a few days went by the images of the post impact swivel video faded and the pre-swing routine became take club back to position then forward to impact position and hold. This is when the pushes started.
Doing the one-plane as per Jim Hardy instructions my left wrist folds back after impact so it becomes doubly important to rehearse the finish swivel before each TGM swing (at least with driver)
I am just smashing my iron shots lately, have to reassess distances now.
Incidentally, I believe I'm a hitter now that I read and think about it..