How did you get 32? I would have said 3*8=24. TBH I've avoided mentioning anything about multiple UV sets as I don't know enough about them. If I was guessing I'd say extra UVs are handled differently as they probably don't influence the bitangent calculations. UV counts ARE closer to the real number than XYZ counts but…
I think EQ just mean't that the vertex counts won't increase if you make a hard edge in a spot where there is a UV seam already and vice versa. Calculating the vertex count takes in multiple factors, but he is right in saying that the closest number to it is usually the UV count. Remember each UV channel also adds to the…