There's going to be some changes ahead with new books I'm working on. I'll be removing some of my less popular books from Amazon and placing them on my website for free while adding new content on Amazon. There's no limit to how many books an author can place on Amazon but I feel it may be a good idea to remove the old less popular titles before replacing them with new books keeping everything fresh so to speak.
I've noticed over the years that it tends to be short stories, 30 pages or less, that tend to be popular on the Kindle which I put down to readers not wishing to commit a lot of time to a book. If it can be read in one sitting then all the better.
I've been looking at advice online about how to get the most out of selling via Amazon KDP, some of it good, some of it not so good, and I've reached the conclusion that it's rare for someone to make a living from it unless they are already professional writers to begin with. I'm aware of the trick of writing what's known as low content books, such as books of quotations, internet memes and so forth, but that's not really my style. For me I personally want to create the content myself rather than just sell it.