No, we would frequently dig in our tanks while on the defense. Even our gunnery ranges have a semblance of a dug in fighting position for some of the engagements. On an M1, the sights are on the very top of the tank....so while dug in, you can hide, using the sights like a submarine’s periscope. You pull out of the hole to fire...and back into it quickly to hide.
I’ve never seen an M1 in the hull down position. Their tactic is to advance at rapid speed and fire on the run.