Follow Through Animation

Here is my tail animation. I really didn't expect this to be so frustrating. In the end, I think the tail still doesn't look right. I just noticed that even though I traced really carefully, the cat does move! This makes me wonder how people animate those complex animation (especially anime) having to draw and paint every single frame. I also wonder how much time the animators have saved after switching to doing all 2D animation digitally. I mean, would they still have to draw every single frame?