I'm not sure they need the in between areas, so long as the landmarks are inclusive of similar features. In fact, they probably only need a high quality 3D scans of primitive features to perform classification (walls, building, intersections, etc). I haven't played recently, so I'm unsure how distinct each landmark is.
> I'm not sure they need the in between areas, so long as the landmarks are inclusive of similar features.
That gets you good navigation around landmarks, but when you go further away, you get less usable feature points, as they are closer together you get more position error/need higher resolution cameras.
The intermediate places gives you the precise consistent navigation.