I love how we all have such different ways in sorting, or not sorting our books.
I don't keep all my books on my Voyage either, but I still have them all in collections. I change to cloud view to see them. I keep about 50 or so on my device that are books I am planning on reading in the near future.
But I must have every single book I own sorted in collections. Once in a while I browse through my collections and when I see something I might move to my reading next pile, I can easily do so.
I also browse through the calibre library or my goodreads shelf to do the same thing. I need more time to read all the books I keep organizing.