You always was able to animate more than four frames. However, you were limited to four frames per second. If you want to increase the amount of frames per second, you have use multiple slots because each ExGFX slot animates asynchronly (more specifically, each slot animates one frame later than the previous one) and split the animation in these slots (e.g. slot 0 only features frames 0, 8, 16 and 24, slot 1 1, 9, 17, 25, etc.).