My publications are long; should I publish long books or serialize them?

There are two issues here.  First, if it doesn’t make sense to split up your books, there is no reason to and you should submit it as a single work.  The beauty of a digital format is that you don’t have to worry about “bulk” when trying to read a long work, and you can price short works cheap enough to justify selling as stand-alone pieces. Each work should be as long as it needs to be and no longer and no shorter.

That said, there are a lot of examples of serialized fiction on Amazon.  In fact, serialization got so popular that Amazon created the Kindle Serials program a few years ago to provide a better outlet than the ways that their marketplace was currently being used (right now, you need to sign a publishing deal with one of Amazon’s publishing houses, such as 47 North, in order to have access to the Kindle Serials program.)  The way that that program works is that every week or two weeks, a new “episode” in the serial is released and automatically added to the end of your book (with all of your bookmarks, highlights, and read locations preserved) and then at the end of the novel you are reading they release a paperback version and bump up the price of the serial to a standard book price instead of the discounted price it starts with while being serialized.

To my knowledge, Amazon no longer signs new books for this program and so it’s unlikely to ever be available, at least for the foreseeable future.

There are publishers that put out serials as distinct books for each “episode” of the season. Basically, they become shorter series books.

If you want to maximize the exposure of your books, you could release them as a whole, and then release discrete parts that then reference the whole. Just make sure that each piece you sell has an accurate description of what is being sold inside that book, and that it’s enough information to be useful (for non-fiction) or enjoyable (for fiction) – you don’t want to split up a book by chapters unless each chapter is a discrete element that could be sold on it’s own merits. Include a link to the complete book as a collection of all the discrete parts (and potentially include the links for each discrete part for somebody to pick and choose.) When pricing your works, make sure that there’s a good discount to be had by buying everything; if somebody purchases 1 of the parts, the cost of the whole work should be less than it would cost to then purchase the remaining works individually.