you got to divide each room if you plan on flowering at different times, but if you plan on flowering all plants at the same time, you can, basically, if all your plants are of a stable strain, then you could flower them all at pretty much the same time, with little variations in plant height.
but i have yet to come across a plant, that grows exactly the same, each planting, from seed, now clones on the other hand are a completely different situation