There's this map (http://knucklecracker.com/creeperworld/mapcomments.php?id=1163) that has a lot of crazonium walls.
At one place I thought two relays should be able to connect since there was a thin space between two walls, but they could not. It may be that it is out of reach of relays, but perhaps there is a LOS calculation issue?
(http://i43.tinypic.com/20f6iwh.jpg)
Note the bottom where I circled, and then compare to the top, left, where, to my eyes, the only difference is that the top has more space and only a wall on one side.
The line goes from the center of the buildings, so that would have to go straight through the middle of that top wall.
If the Relays were each one block lower, then it would go through.
Indeed, but one could argue that those towers have LOS of each other....
The cells that they are centered on don't. That's what counts.