Usually if the animation is "complicated", it is
most likely the main animators doing that
sequence.  Or at least that is what I am guessing.  

From from what I have seen, evident key cels (A1,
END, "circled" numbers) are not always valued more
than "regular" cels that do not have THE SIGNS. 
There are cels that don't show the DEFINITE key
signs, but their complexity may indicate that they
are and are valued just as much.

Sorry if this sounds confusing.  It is Wednesday
morning and I am still trying to figure out my
Chem homework!  *Sigh*

J-Decker