While I was reading through a very interesting Ward Kimball interview by Thorkil B. Rasmaussen in Walt's People - Volume 3. There was one part of the volume that really interested me and the way Kimball explained it. The interview was conducted in 1978, and at the time Ward was teaching an art class once a week.
Here is a part of the interview that I like:
TR: I know that you (the Disney Studio) are looking for new talents for future productions?
Ward Kimball: Yes, but you see, today we don't have that great training ground called the shorts. We all worked on shorts, but we didn't have to be quite so exact; we could get away with small tricks, but you can't do that on a feature. So they don't trust new guys to take over whole sequences. But when you rehearsed and were trained on the shorts in the early days, you began to be noticed as a qualified animator. Then you graduated to the features. It was a stepwise evolution that they don't have today. You just don't learn everything sitting next to an animator. You learn by doing the stuff yourself.
The person conducting the interview, was talking about the future generations when that the old animators will have to retire and the newer generations of animators will have to take over. It seems that from Ward's point of view that he was explaining about that the problem with new animators is that in the 1970's - there wasn't any animated shorts being produced, and only animated features and live-action movies. The great animators that were considered veterans by the 1970's, all learnt from working on the shorts like a Silly Symphony short or Mickey Mouse. The process was being made until shorts were abandoned by Disney mostly until the early 1960's.
Of course, there were good animators at the time who were very capable of animating whole sequences like Don Bluth, although as Floyd Norman has mentioned: Don was one of the animators in the "middle group". While there were the older, more experienced animators (born around 1900's and early 1920's) and there's the younger animators (1940's and 1950's), and the middle group were born around (late 1920's and 1930's).
Ward is right in a way that if you were working on a short, you could get away with the crude animation in it, even though there were tons of animated shorts produced in the Golden Age with some crudeness into it. Walt Disney has always wanted realism into his shorts, so that's probably why the 1930's shorts resulted with some crude animation, either because an animator attempted to do its best and ended up animating as a bad result, or that they knew they knew they would get away into it.
That's probably why younger animators were not trusted by the directors and the producers to animate and plan the entire sequence, because they feared of the little amount of experience they had and that the results will be bad. The supervising animator planning a sequence is clearly shown in The Rescuers where there were junior animators like Gary Goldman, Andy Gaskill, Ron Clements, etc. doing bits of animation in several sequences. About every sequence in the film has a Supervising Animator or a veteran animator planning and animating much of the sequence, making sure that the character animators wouldn't screw up a scene - it seems that guys like Frank Thomas, Ollie Johnston, Milt Kahl or Cliff Nordberg kept a special eye on them.
I suppose that the "shorts" was no longer created for Disney animation in the 1970's and it led to Eric Larson becoming a mentor for the all-new Disney training program. By the The Fox and the Hound and Pete's Dragon. The young animators were on their own, it was up to them to have the confidence to make these pictures real - and Frank Thomas, Ollie Johnston, or Woolie Reitherman were not there to help them as they would be in retirement, with Eric Larson preparing them by mentoring them.
Even Kimball mentioned that you "couldn't do tricks" on a feature. I wasn't too sure what me meant but I suppose he was talking about that crude animation wasn't allowed on a feature. Of course, there has been crude animation that somehow survived into an animated feature, even at Disney.
I'm going to leave my little talk. This is part of a Ward Kimball interview in Walt's People - Volume 3. I definitely recommend that you should collect the series of them edited by Didier Ghez. He's published ten volumes of these so far, and they're all worthy. I haven't got all the books myself, but I'm slowly collecting the series, I'm currently looking forward to Volume 11 for some more surprises.