When looking through the Archer gallery, you will see a bunch of rough animated gifs like this:
These are the keyframe animations that the illustrators create for the character animators. Once the animators have all the parts they need, they will fine tune the action by rotating parts to fill in the gaps between each keyframe. This method of "puppet animation" provides animators the elements needed to create fluid movement using minimal drawings. For example - a 2 second traditional animation would need up to 60 frames(drawings). The same 2 seconds above was created with 7 drawings.