I remember that library, that's an interesting idea. I haven't seen anyone else with a setup exactly like that. I would fear doing that with a larger collection though due to the work required to replenish the shelves should someone take all the books.
I've seen a few interesting library variations actually. Revolving collection libraries, where 50-100 book sets are rotated every month or so paired with a theme for that month, fully thematic libraries, and of course the classic standard library setup.
Personally I've worked on perfecting the classic setup for my own library. I purged books from other shards, books with little relevance, and most OOC works to keep quality high. Over time the quality of books became more important than the quantity, especially since I've maxed out my lockdown limit currently with minimal decor and 1500+ books on the shelves, and about 800 more waiting to go out should lockdowns increase. Had I kept the low quality and irrelevant books, it could have easily topped 3000.
In terms of organization, I've organized each book shelf by topic, dyed each book a color to correspond with that topic, alphabetized every book, and created a master list of each book per shelf to assist in finding books easier.
Taking it a step further, I had actually created a better organization system for large libraries based off a specific setup. However I need more lockdowns to implement it properly. I'll list the setup I thought of below:
For the system, the pack number will be recorded (I.E. Pack 1, Pack 2, Pack 3)
The new recording scheme will list the row number (1 - 5), as all bags will be arranged with 35 books per bag divided into 7 books per row.
Each shelf, along with a category, will have a number assigned to it (IE, Shelf 3 - Legends and Tales N-Z)
The master list online will be updated with the shelf, pack, row, and book number to make it easy to find books.
For example, the book "The Life of a Bard" could be found in S3 P1 R2 B4. (or "3124" to make it easier)
This shows The Life of a Bard is in the Legends and Tales (N-Z) shelf, in the first pack, on the second row of books, and it is book number 4 of that row.
The goal is to have a quick, easy system to categorize 2000+ books, while still keeping an organized listing that people can browse on the fly.