The size of the brood nest (hopefully) increases as a hive grows from a split, a swarm, a package or NUC. The space needed for the brood nest is smaller in the Fall and over winter & larger from late Winter and early spring and summer. I don't like to use queen excluders that much so I try to keep the brood in one or two boxes, depending on how robust the colony is. I will use an excluder to limit the nest to two boxes.
My favorite is a Deep and a Medium for the brood nest, but I don't think the bees see it the way I do. I have gone away from using medium supers & largely keep just deep hive bodies and supers. Having one size makes managing hive bodies and frames a lot easier. JMO
We are coming up on the Fall. I will consolidate all brood in the lower box as they go into winter and, if necessary, feed until I feel they will have the stores they need to get through the winter, (I realize this consolidation is optional). My bees do better and have a good population early, (meaning, a big population for an early honey flow), if they have plenty of stores and do not need to be fed in Spring, (it's a lot easier on me too).
Most important thing for the bees now is mite control. The bees are raising the bees tasked to overwinter here in warm Texas. The healthier these bees are, the better the hive will come through winter and make a good population explosion to gather the Spring honey flow.