When the film Sleeping Beauty followed Lady and the Tramp in 1959, audiences were in for a surprise. All of a sudden the styling, for both backgrouds and characters, had become flat and graphic. Sleeping Beauty looked like a Renaissance painting come to life, while Lady and the Tramp had a Norman Rockwell feel to it. Quite a few animators needed to learn how to draw "flat", but keep the movements dimensional. Not an easy thing to do. For animators with superior draughtsmanship like Marc Davis and Milt Kahl this became a fairly easy task.
What about the key clean up assistants? One of them, Iwao Takamoto, made the switch just as easily. It is fascinating to compare these two drawings by Iwao. His clean up study of Lady looks like a sculpture. Round, dimensional forms that had been so typical for Disney's animation style. Aurora on the other hand looks like a beautifully designed paper cut out.
I don't know about you, but I love BOTH styles.
Here are links to earlier posts on Iwao Takamoto:
https://andreasdeja.blogspot.com/2014/01/iwao-takamoto.html
https://andreasdeja.blogspot.com/2016/03/why-this-scene-looks-so-amazing.html