/jp/ - Otaku Culture

Tweens: This is the step that is farmed out to Koreans. It is considered menial labor and therefore no credit is given. Even before Koreans did the bulk of tweening, this was the job given to entry level animators. Although it is the most polished of all the steps, and results in the final product, it is expected anyone in the industry can do it, and there is no creative input.

Good tweening will simply result in smooth animation that does not appear awkward.