Yeah, I think the limit will be 15 indivisual frames. Then I usually reverse the order of the frames to make animations that are around 29 frames. Anything over that takes too long to do. Also, I usually make a couple animations for people to choose from. If you know exactly what you want, then I suppose I can make it a little longer, but otherwise it's best to keep them short so I can give you a variety.
I'm feeling a little better, I'll start making them again on monday.