2-lane roads have to be doubly connected to work - that is, both squares on a side have to be connected to the same thing, either another piece of 2-lane road or the town hall. I doubt zig-zagging the roads would help, but it won't work anyway.1) How much support the buildings in a city will need varies wildly according to city plan. Some are much more efficient, some less so. Moreover, you might be able to get more use out of two lane roads by placing them in a zig zag pattern so you have more surface area to work with. Given your sketches, each two lane road segment is connected on four squares to other 2-lane road segments, leaving only 4 squares to connect stuff that needs it. If you zig-zag the road you might be able to only connect each square of two lane road on 2 squares to other 2-lane road segments, tus allowing 6-squares of the 2-lane road segment to connect to buildings which require two-lane roads. Regardless, until now, you did not take anything else into account other then the size of the structures themselves when computing per square efficiency, and that seemed like a good rule to follow.