Depends on shelf spacing, but when I regularly pushed truck in that area, I did 4 of the Fieldcrest and 5 of all the other ones. Any more and the ones on the top shelf tend to tip over while the ones on the shelf one down from the top tend to snag on the tiniest flaw on the underside of the top shelf. And it was only 1 stack, not two deep.
But then I'm one of those people who likes to shop a neat, tidy store. Which is why I keep the clearance end caps in my area at least somewhat tidy. Wonder of wonders, I notice that they sell down a whole lot faster these days, far less goes salvage.