We've seen that Metal Sheet Walls don't fit tightly together and will create a little crack that you can look through, regardless of how you place them.

Screenshot below is just proof. They will not get close enough to any other building to close off the crack and the only way of closing the crack (somewhat) is to place a Pioneer Post behind or in front of the crack.



Don't ask how I navigate in the dark.. I don't I just pray and hope.. :P