My first Calibre library I dumped many thousands of books into it, with a very complicated workflow to handle duplicates, cleaning up author/title names etc. Along the way I changed my mind multiple times about how I wanted stuff tagged, how I named authors and series, how I recorded books read etc. It was very time consuming and Calibre performance degrades with massive libraries (much less now than it used to though!). I ended up with a huge library of books but I had no idea which were actually "readable" to a standard I would find acceptable for sending to my Kindle. I tried cleaning up the library over time and marking books with tags when done but it was too depressing for me as I never felt like I was catching up and the "good stuff" was lost amongst the mess.
The OCD in me just could not cope with having an inconsistent library or the ever increasing duplicate problem as you add more books. So I started again with a fresh library and use the "Copy to library (Delete after copy)" menu option or add from my file storage to migrate stuff author by author. I then grab the best covers & metadata I can find, create empty books for stuff on my wishlist to complete the series for that author, convert if not already to the best quality EPUB and edit in Sigil to get to my picky standard, delete all other formats and then convert to MOBI, so I have versions for my Kindle and any future device (from EPUB). Only then do I grab another set of books to add...
At least this way I am as confident as I can be that a book I put on my device or share with friends/family it is ready to be read and enjoyed. But each to their own
