My bread machine makes vertical loaves, and I always make the two-pound
size. The amount of rise seems to vary from loaf to loaf, even with the
same recipe, but at least no matter what amount the dough rises, I have a
loaf of bread at the end which I can slice for sandwiches. It is
completely filled out from side to side but the height will vary, so the
number of slices yielded varies accordingly.
What happens in the case of horizontal loaves? If the dough doesn't rise
as much as it should, I would think the resulting bread would be flatter,
and therefore, would not produce decent sandwich slices.