I think you should read what Michael Bush has to say on the subject. He's in a colder climate than I am. Closer to what you might have, there in Michigan. What I experience, here in Tucson, would be no comparison for you.
- / - / - / - / -
I run primarily 8-frame medium size supers, throughout. With my equipment configurations, I can rarely get the bees to use more than two 8-frame medium supers for their brood nest, but at the peak of our main flow, they do use nearly every bit of that space for brood. Whenever I've added a third super above the existing ones, they've always used it for nectar and pollen storage, immediately above the two that are below, full of brood. In the future (next season), I have plans to see if, I can sneak a third brood super into production, if I place it between the two existing brood supers, rather than above them.