Sharon, my opinion. The brood box should contain two deeps, allowing the queen to have LOTS of room to lay, the shallows for honey. But, there are other members that use a deep and two shallows for the brood chambers, the queen must have lots of room and the bees must also have lots of room to store the nectar, picture how thin nectar is and then how thick honey is.
That is a lot of evaporation that must take place for the nectar, and it takes room, lots of room. So many posts on this subject about room for storing nectar. Have a wonderful day, great life. Cindi