[LSH]

Still very still - as yoda once said (paraphrasing) - Homer used the word stationary for a reason.

Any head movement in the stroke would move the low point and impact point of your clubhead orbit. Your left arm and clubshaft and head form a radius., If you move your head, you will move your radius of that clubhead orbit

Last night I hit a couple bags of balls. My first few hits with my gap wedge were pretty good, then I started hitting down on a steeper angle. The ground was dry and hard so it was quite noticeable in difference in feel. I think as happens too often my first few swings are easier and smoother with little or no head movement or sway. Then I start swinging harder to hit it further. I may be pushing off with my back leg too much. But at any rate I get sway and head movement causing various direction and trajectory changes.
As a side question, do you focus on a specific point on the ball or look at the ball as a whole and swing through that place?
Steve