No cities bigger than 3 streets generating

Made a new world, tried setting it for bigger cities but further away from each other than vanilla. Result: so far have found only 3 “cities”(and there are 3 more somewhere else judging by overmap screen). One of those is 3x2 streets, another is 4 houses, and the last is called a city but really is just a crossroads without any houses. The world was generated on one of latest experimentals about a week ago. Bug or some intricacy of mapgen options I’m not aware of?

    // spacing dictates how much of the map is covered in cities
    //   city  |  cities  |   size N cities per overmap
    // spacing | % of map |  2  |  4  |  8  |  12 |  16
    //     0   |   ~99    |2025 | 506 | 126 |  56 |  31
    //     1   |    50    |1012 | 253 |  63 |  28 |  15
    //     2   |    25    | 506 | 126 |  31 |  14 |   7
    //     3   |    12    | 253 |  63 |  15 |   7 |   3
    //     4   |     6    | 126 |  31 |   7 |   3 |   1
    //     5   |     3    |  63 |  15 |   3 |   1 |   0
    //     6   |     1    |  31 |   7 |   1 |   0 |   0
    //     7   |     0    |  15 |   3 |   0 |   0 |   0
    //     8   |     0    |   7 |   1 |   0 |   0 |   0

Yeesh. I for some reason assumed spacing works in kinda linear progression… but it is actually closer to geometric. Thanks, that answers my question.