I' sort of getting it. In a sense we wouldn't need to necessarily make sure that all the sewers linked up, as long as they didn't cross over the boundary lines. If that's the case then that's a lot easier, because dungeon enthusiasts could do as many sewers as they liked on their own property, while those of us who prefer building interiors or many levelled towers could do that either instead of or as well as the sewers... (I think)