I'm watching Adventure Time and I have noticed that some episodes have an amazing animation quality while others are so badly drawn compared. They seem to change the artist at some episodes or something. I have noticed this also in Avatar, The Last Airbender, but only happened in a very few episodes (Maybe for vacation of the main artist), in the case of Adventure Time this quality drop happens quite often, at least at the second season which is the one I'm watching now. Anyone knows why this happens?
It's probably because the show is animated by two different studios, and because the process involves hand drawn animation.
Adventure Time then contracts their animation out to Rough Draft Studios in Seoul. Founded by Greg Vanzo and his wife Nikki during their work on Ren and Stimpy, Rough Draft Studios has animated some of the most well known properties in cartoonery, including The Simpsons, Beavis & Butthead, The Poweruff Girls, and Futurama.
About three months later, the fully animated product is sent back to America where final changes are reviewed and implemented. “There’s a round of retakes, where we look for mistakes that might have been made or things that didn’t animate the way we intended.” Osborne says. “Then there’s a few weeks of sound design where we add effects or record additional dialogue.
Note that the show is hand drawn, as explained by Andy Ristaino:
My dad and i are arguing how Adventure Time is animated. Is it fully hand drawn every cel frame and inbetween? (he says its not possible) or is it rigged/inverse kinematic? or a mix of other things? help please and thank you(:
except for a few instances, like in guardians of sunshine where we use 3d, all the animation is hand drawn.
The Wikipedia page contains more relevant information WRT the making of the show.