I still think the layout is essentially the same. The orientation of the 15 zones is what determines whether it is POSSIBLE to just cross a border between them. It doesn't mean that you necessarily can. If you think about it, City of Mist of Eel Infested Waters COULD have been anywhere on the map, as far as travel was concerned. There was no way to walk or swim across a border to get there. You could only go by ship.
So 'detached' zones, like Emerald Isle or the Planes, could be physically located virtually anywhere in that 'grid' of 15 outdoor zones, as long as you didn't build a simple border crossing into them. They may not show up on the map that way, but I strongly suspect that they were still laid out within that pattern as far as the game engine goes.
If there were only 14 in one of the games (and I haven't played either 7 or 8 in a long time, nor do I have them loaded up), then it may just be that they left one available zone unused.
There's only one way to find out though.
