Is there any reason to only use one instead of two?
Last year I tried to figure out how much room was needed for
a brood nest. Alot depends on conditions, but it is very close to
three mediums or two deeps.
Modern queens have raised to use 2-3 brood boxes. There are pollen and honey in boxes too. And you should have free space for heavy nectar flow so bees have room to dry upp nectar. Why to keep them tight?
There are bee stocks which are not able to use more than one brood box but those days are 40 years away.
I use unlimited brood area. I want much bees so hive is able to handle huge amount of nertar from rape field.
If hive is small 2-3 boxes, it fills a hive during one week and then it swarms. Small hive and huge nectar flow does not match.
Here is my normal foraging hive. I put 2 weak hive together in order to get one normal. Here I move hive from rape to fireweed. After 3 weeks it has 240 lbs capped honey in one time. Brood area was 2 palm size.
If I have weak hives, I miss the yield and bees. I live 100 miles away from my hives.
40 years ago normal hive has 2 boxes: one for brood and one for honey. Normal yield was 30-40 lbs.
If you have small hives you should watch them all the time.
You may calculate space for honey:
medium box 30 lbs honey (8 frames in 9 frame box)
langtroth 50 lbs honey (box 10 frames)
It is possible to have about 150 lbs capped honey one time in this hive and then you must take honey away and give empty boxes. When nectar's is fresh, bees need really much space for handling. otherwise you get swarms.