It takes longer to make a wall the way you want out of multiple pieces than it does to just make it exactly the way you want.
What I mean about things lining up is that you can’t take a mesh to be the floor and scale it so that it extends underneath the walls to cover the whole area, the part under the walls will receive shadow and that will bleed onto the insides of the rooms. Or if it goes outside the building then the light from the sun will bleed onto the inside.