One layer has body lineart, one layer has body colour, one has mane lineart etc. I hope that somehow explains layers. I had to type this in a hurry.
Actually, it wasn't a problem at all, even though the other people are usually using like 10-20 layers with a single drawing. I also have heard them saying that I should avoid using that many layers, because it's easy to get confused. Well, I haven't got confused yet, so I guess I'm doing it right.