Gameplay element I'd like to use in a map

Well, it's feeling about time that I take another attempt at making a map.
I've long thought it would be interesting to require players to attack through neutral territory to conquer an entire continent. This already happens when a "continent" is simply a set of diverse goals to hold for a bonus, but what if the continent was still a physical location, but with impassables dividing it into two or more pieces?
That line of thought brought me to the following setup:

This would want this to be just a part of a map. The entire "north wall" would be a bonus, but the outer "north wall" territs cannot attack the inner "north wall", or the central "north wall", without going through the corners first. I realize this would make the corners incredible bottlenecks, but I don't think this always has to be a bad thing. Holding the corners would be key to holding a wall, of course.
But my question is simply this: do you think such an element as what I drew above can be used in a map, or is something about its setup inherently bad for gameplay?
I've long thought it would be interesting to require players to attack through neutral territory to conquer an entire continent. This already happens when a "continent" is simply a set of diverse goals to hold for a bonus, but what if the continent was still a physical location, but with impassables dividing it into two or more pieces?
That line of thought brought me to the following setup:

This would want this to be just a part of a map. The entire "north wall" would be a bonus, but the outer "north wall" territs cannot attack the inner "north wall", or the central "north wall", without going through the corners first. I realize this would make the corners incredible bottlenecks, but I don't think this always has to be a bad thing. Holding the corners would be key to holding a wall, of course.
But my question is simply this: do you think such an element as what I drew above can be used in a map, or is something about its setup inherently bad for gameplay?