I have just started using virtual libraries. Still figuring out where it brings value to me. I have VLs for the reading status and for book series / book universes for now. The most useful it feels for the Cosmere and treklit as these are meta-universes.
It's probably also useful to separate the Star Wars legends EU and the SW "canon" EU. But that's a rabbit hole that I don't want to go down just yet.