I’ve never seen an M1 in the hull down position. Their tactic is to advance at rapid speed and fire on the run.
I was an M1A1 Tank Commander. We dug in all the time.
We would typically have an Engineer BN tasked with us, to dig the holes.
In the Army, you are usually holding ground or taking ground...and if you’re holding it, you dig in.
The engagement you envision is a ‘meeting engagement’. We would train for that too, but not all the time.
I can’t get my html to work, but here is a link to a straight M1 in Hull Defilade:
http://www.steelbeasts.com/sbforums/sbgallery/main.php?g2_itemId=2954