What can be easier than a "recent" list in a books app? Sort the list of books by the time they were last opened.
Here's how Apple books does it:
- iOS, "Currently Reading" tab. Recents show recent books, in correct order, but doesn't show all of them. It randomly skips over some books and displays other
- iOS, "Your Library" tab. When sorted by recent, shows recent books in correct order, and shows all of them
- MacOS, "Library" tab. Sorts by recent... as they were opened on your computer, and never synchronises the recent list with the iPhone
Because, you know, reasons.