Books are afaik placed randomly in the Bookcases of the world. And with a different distribution when you change zones. Possibly different distribution per player too.
So at tops we could tell you where all the cases are.
Maybe tell you wich books you already read. But you would still have to use all bookcases.

I'm under the impression that books are randomly placed on bookcases by the game engine probably at every game log-in, But I've noticed that some locations will have the same book for days at a time over many multiple log-ins.

Is this still purely RNG, or maybe some bookcases are so unimportant as to be out of the loop? It was a real surprise when the bookcase near the enchanters stations in the main crafting room in Elden Root changed after almost a week, and the ones in the Mages Guild off the same room tend to be static as well.

Those were the bookcases I checked most frequently since Librarian database file was borked for me with the API issue, and I was just constantly sampling them as a lark every time I logged in.