That said, it still surprises me that these map makers (all of them! not just this one) don't take the simpler approach of drawing all dots in a random order - e.g. get rid of this "first all blue dots, then green, etc" behavior, and pick the next dot's color randomly, while maintaining the distribution. Then you'd have an unbiased "top layer" regardless of the size of your dots (up to a point, obviously).
(hard to describe what I'm thinking of... basically `[red, red, ... * 25, green, green, ... * 10, orange, orange].shuffle.draw` rather than just `[].draw`)