bread machine loaf size buttons My sunbeam 5891 does not give specifics on the knead/rise/bake times of each cycle, or what happens when you change the loaf size.  Time slightly increases if I click the button to raise from 1.5 lbs to 2 lb loaf.  Does proofing time, baking time, or both increase when the 2 lb button is used?

My goal is to add 10 to 15 minutes of proofing time for particular recipes.
I doubt it'd increase the proofing time, since that doesn't generally vary with the quantity of dough; the yeast is working in all the dough at the same rate. It would definitely need to increase baking time, though, since it takes longer for heat to transfer all the way into a larger loaf.

Sounds like with that machine you might have to do some non-automatic proofing in order to increase the time, e.g. with a preferment.