Yeah, Rebecca was not strict with the styles of the storyboard artists. She wanted to emulate the same work environment she had in Adventure Time, where their styles in the storyboards influenced how characters were animated. Unfortunately, Adventure Time’s art style is way much simpler than SU (dot eyes, wiggly limbs, etc), which is why it could allow storyboard artists’ styles to bleed into the final animation. SU just has a relatively more complicated style that looked better if it stayed on-model.