Use a ready-made set of 21 facial expressions for characters

Every movie has characters, which must show facial expressions (and body language). According to research, there are 21 facial expressions in total (see the photo at bottom).

Another research states that there are 35 expressions across different cultures .

The non-human characters (monsters, robots, animals) have limited facial expressions.

It is too tedious to animate each character throughout the duration of the movie.

So why not have a built-in set of named expressions? (examples: calm, happily surprised, confused+angry, sarcastic, skeptical...)

Then the animator can just assign an expression to a character's rig from time T1 to T2, adjust the intensity (mild-to-wild), and that's it!

For example, if the screenplay says that Harry Potter says something to Hermoine, both characters can be assigned suitable expressions from a drop-down list. That would cut down the rigging time drastically.

A subsystem should handle the lip-movement, so that the characters can talk while showing any of the 21 expressions.