One month before the Charmed Novels were announced Paul talked about them and the idea to be serialised during an interview at the NerdFap Podcast. You can listen to it here from 37:12 to 38:15.
Paul Ruditis: I’m working on a project right now, unfortunately I can’t talk about but it is very exciting because we are doing digital-first. We are going to launch it digitally. Right now the plan is to do it in sections so it’s going to be serialized; it’s going to be a serialized novel that if it sells well enough will then become an actual physical book and it’s really great because there are different ways you can do this. I worked on an idea, unfortunately the idea didn’t wind up going anywhere but this was a few years ago where I was working on the concept for a series that was going to be the same thing where it was going to be very heavily serialized like the old serial movies where everything ended on a cliffhanger. The way we are approaching this is we are actually approaching it as if it is one contained novel. It’s going to be serialized but it’s going to be broken up in a way that, you know, it depends on where it might be broken up. It might be broken up in the middle of a chapter. It might be broken up where one section has 40 pages, the next section has 50 pages and then you get to experience the story as it unfolds over a period of months or save it up and read it at the end.
While "The War on Witches" will be released as a full ebook, the plan for the rest of the books are to be serialised. Paul talks more about this in the interview i had with him earlier this month. You can read it here.