A lot of the discussion in this set of tutorials has been focused around square geomorphs. They're the easiest for most people to wrap their heads around. But my preferred form of geomorph is based around the hexagon, these tend to produce more organic and interesting shapes.
This is true for natural environments, but it's no less true for urban environments.
The example set of geomorphs above as a simple two-phase system. One edge type is plain, the other edge type has a road piercing the centre. There could be dozens of combinations and permutations for each of the two phases around the hexagonal edges, but a quick look at the variety of buildings and road shapes shows that there could literally be hundreds of possible options when drawing these map fragments.
But you certainly don't need to create hundreds of designs for the system to be effective. Using only a dozen different designs repeated, a huge variety of urban environments could be mapped out. Each additional geomorph adds new versatility and a wide variety of options depending on how it is combined with the existing map fragments.