The secret of good animation lies in the planning, and experienced animators know that by drawing clear thumbnails to plan out their work, they can save a ton of time in executing their shots. I have always used thumbnail drawings to plan my work, but seldom (to my regret) have I saved my sketches - most of them hit the bin long ago. But one animator who has saved a ton of his planning sketches is Pixar's Victor Navone, and you can see his thumbnail gallery here.
