I regularly clean out my eink reader. There's typically 2 or 3 books on it, and rarely more than 10. My main reason for an eink reader is to have free and hassle free access to public domain works or library books, and because it's mildly more portable. I don't see much of a point in carrying a huge library of novels with me.

The LCD reader is a bit different. It stores reference works, so titles get added to it and rarely removed.