I have a bookshelf modeled and a group of 10 books (so as to not make the bookshelf look repeated), is it possible to create a driver to just drag up/down the amount of books on the shelf???
You could use particle system to emit the books from vertices:
The emitter is a subdivided plane, the origin of the book group (only 3 books on layer 2) is set to the bottom of the book.
Uncheck Random under 'Emit from:'
Related: Prevent particles at the same place?