one book.bib or many?

Does anyone have any experience or thoughts on the best way to manage book.bib & package.bib files across multiple books?

I now have three books on the go & there's a big intersection of reference materials. Maintaining the same content in three separate projects is getting to be a bit of a challenge, so I am now thinking of having a separate project / GitHub repo to house the book.bib and package.bib files.

I don't use .bib files, but I have over 10 books going, and I needed some things to be the same for all of them. I created a separate repo for those files and I clone that repo and pull them in at build time.

It works great.