The problem is that when a map has animated tiles with different frequencies, the overall animation period of the map is the least common multiple of the period

The problem is that when a map has animated tiles with different frequencies, the overall animation period of the map is the least common multiple of the periods of the single tiles. For instance, a map covered in tiles with 10 frames will also have 10 frames. But if the map has, say, both tiles with 10 and 11 frames, then the period of the map is 10*11=110. Basically, maps containing different animated tiles can potentially have lots of different screen states, while maps with the same tiles have a low number of screen states. I think maps full of the same tile repeated wouldn't be a problem so the threshold might work in pretty much the whole game.