It's a good way to improve construction and use of easily animatable shapes by studying how the masters did it such as Milt Kahl's early work. In order for a design such as Brer Rabbit (or any animation design for that matter) to animate well, the details have to fit into the larger forms and appear to wrap around it like a puppet, or anything three-dimensional). The fox's head, in the bottom right corner, I doodled to demonstrate how eyes would wrap around a spherical form, the head; it's rather exaggerated but does the job.
Most of my notes are proportion related which is my biggest weakness when it comes to observational drawing.