I notice on some posts here the implication here that there is something WRONG about characters not being "on-model" from shot to shot.
please watch Rebecca's pre-SU work
Now keep that in mind, and think of say the design of characters of southpark. You make a bunch of screenshots and and copy one character from the side, front and back and you've pretty much learnt to draw them, they have a bunch of stock expressions pre-drawn and you swap them in and out to make the new expressions. This is a 2d animation method that imitates paperdoll animation (south park's pilot was literally done with paper) and it's quite obvious in south park, but things like MLP, House of Imaginary Friends CN cartoon (parahrasing the name sorry) and Rick & Morty use it in a much more subtle fashion.
Now, take say Ren & stimpy. You copy Ren from the side, front and back you just know to draw a specific moment in a specific episode, because he was often changing his body and face structure for each new shot and frame. This is because Ren comes from a school of specific acting that pretty much started with the original Looney Tunes, https://2.bp.blogspot.com/_mJ4lc_Q9Q6k/Sxroc2v-FlI/AAAAAAAAj5c/ABRBpYLa2jg/s400/43bugsClampettmodel.jpg Check out this model of bugs. there's much more there than just side views, there's a bunch of expressions. These werent the limit either, this was pretty much just keeping track of what they had already done if any situation called for something crazy and new they would do it, an you can thank this for all the crazy SU meme faces.
I used Ren from Ren&Stimpy as an example because his creator John Kricfalusi is a biiiig proponent of specific acting, his blog is where I got the term. He specifically doesnt draw specific proportions that Ren should have because he wants his artists to break it as much as possible in all stages of production, his model sheets are more examples and it's more about the relationship between the shapes than a rigid drawing for everyone to copy, this is so that everything is unique and the 2d hand drawn aesthetic shines. Makes sense to me, I mean if you're gonna draw ~15 frames per second you might as well try and make them have -some- uniqueness (can also be overdone).
Looking at Rebecca's pre-su work I think it fits far more in the specific acting box than the stock expressions box.
Problem is specific acting is a lot more expensive, and you have to train people to be able to make new expressions. Both Ren&Stimpy and SU are animated overseas, Johnk had to constantly send drawings back to ever get to the level of offmodelnes that he did and so he was constantly late and upsetting his bosses
I was a fan of Rebecca's drawings from Singles, Pug Davis and several other small one off comics in Sougarboukas, so I was disappointed when I started SU that it was not "off model" enough.
I think that because of reasons of costs and delivering on time, Rebecca might have sacrificed SOME specific acting because she had other ways to make her show unique, unlike JohnK for whom it was paramount that every frame was specific acting.
So when people complain about the height differences, about the lack of consistant models across diferent storyboarders, I just have this innate feeling that they're missing the point, because nowdays, even if it's hand drawn you have stuff like gravity falls, like Family Guy which FEELS like stock expression even if it's drawn frame by frame, and this is the idea of quality people might have, but this is NOT necesarily true, people who want specific cartoon acting like me and I'm supposing Rebecca, are actually going for constantly changing expressions that change the drawing of the characters.
Now, that might not be what is going on with every complaint, and it's not like there wasnt a model sheet for even Ren & Stimpy, you cant just draw any chihuahua and call it Stimpy, it was just much more up to interpretation than a stiff Family Guy model sheet, and I dont know all of the complaints that have been made here, I just skimmed a few, but I still thought this might be useful to give people another lens with which to look at "off model".
-not saying SU should look grosser like Ren&Stimpy, I just wish SU was looser like Rebecca's sketches.
-not saying stock expressions are BAD, they have been made quite nimble by computer animation, they can be better than bad specific acting.
-not presuming I'm the one and only hipster Rebecca fan and the only one familiar with these ideas, I just looked up off model here and didnt find anyone saying anything about it :p
https://johnkstuff.blogspot.com.co/search?q=specific%20acting&x=0&y=0 here is a post from JohnK's blog which might show a bit of what I'm talking about. I wanted to fish some of the posts where he explains how he trained the overseas artists to do his "offmodel" stuff and how it went agaisnt their every instinct and it was really hard, but I havent been able to find it.