I agree with Z, more options better than less.
The two buildings should just have different building time and even more if you already have conduits on ground and have to build a conduit wall (because you should have to decostruct the ground conduit and place it in the wall).
The two buildings should just have different building time and even more if you already have conduits on ground and have to build a conduit wall (because you should have to decostruct the ground conduit and place it in the wall).