Advantages and disadvantages of using key shapes to correct pose of a scene I have seen the use of a key shape for a special pose of a scene in This Video.

It looks like a very cool way.

However, this method requires that I bring the character's mesh into editable state for each scene, so it seems impossible to organize your entire work with the Linking Library.

For that reason, it seems difficult to respond to a character's design being modified while working on a shot in a production environment with tight schedule.

In other words, I thought that using a special key shape for each scene would improve the quality of the character animation, but it would be dangerous to apply it to a rapidly changing production situation.

Did I correctly understand the Advantages and disadvantages?
A shape key is a difference effect on a mesh.
So for better controlling faces, or elbows  or shoulders etc.
You can add shape keys, their effect is visible based upon their weight setting. So setting their weight value back to zero will return your original mesh again.

If you worked with linked blend files, sure then you would need to reload(update) if you do this a lot in post production. However one can also create several situations first (angry face/happy etc).
Alternatively if its only a few characters you dont link it, but import it.   

BTW its an interesting video that you found!