No, in animated models, there is no gap between polygons. And if you only compute single-polygon coverage, you can’t determine whether for two polygons that each cover 50% of a pixel, they both cover the same 50%, or complementary 50%, or anything in between. In practice, systems like that tend to show something like 25% background, 25% polygon A and 50% polygon B for the seam pixels, depending on draw order. That is, you get 25% background bleed.