I had a this problem a few times with the large buildings not realizing each small building is independant of the adjacent building even though it clearly should be one large building(hotel, headquarters). I'll have a machine gun crew in the building having to rout of the building right in front of tank or infantry instead of being able to enter farther in the building.
In defending large buidlings, I now have to make sure they have another route of retreat even though the large buildings which aren't necessarily supposed to be small individual buildings.
Would it be difficult to make walls coded as passable/unpassable with adjacent buildings?