Should I split my epic fantasy series into two trilogies?

So I’m working on the first book in a new epic fantasy series, called the Soulbound King. It’s basically a fantasy retelling of the life of King David, loosely adapted from the biblical stories about his life. I’ve already outlined the first book and generated a rough AI draft, which came in at 153k words. The final draft will likely be longer than that, but I think it’s very likely that I will be ready to publish it before the end of the year.

The question I’m currently grappling with is whether to keep it as a seven book series, or to release it as two trilogies with a bridge novel in the middle. Frank Herbert did a similar thing with his Dune books: the first three books (Dune, Dune Messiah, and Children of Dune) were a trilogy, and the next book, God Emperor of Dune, was supposed to be a bridge novel setting up the second trilogy—except he died before finishing the last book, so his son Brian Herbert got together with Kevin J. Anderson to write it, and then they blew it up into a franchise… point being, stuff like this has been done before.

Now, I’m reasonably confident that I’m not going to die before finishing the last book. In fact, I’ve already made a 7-point outline for all seven books, so I know exactly where they start and end, with the inciting incident, midpoint, climax, etc. I’m also writing these books with AI assistance, which is making it possible for me to write these books much faster than I otherwise would have been able to write them. For the first book, The Soulbond and the Sling, I anticipate that it will only take between six to nine months of total work to go from story idea to finished draft.

But the trouble with writing a seven book epic fantasy series is that a lot of readers aren’t going to bother picking it up until all seven books are out. This is because so many readers have been burned by authors like George R.R. Martin and Patrick Rothfuss, who have not and likely will never finish their bestselling series. I can’t really blame the readers for that (though I can and do blame the authors), but it creates a market reality that I need to anticipate and plan for.

So here’s what I’m thinking: instead of making it a seven book series, I’ll make it two trilogies with a bridge novel in-between. The first three books will complete one arc, and the last three books will complete another arc. I’ll wait to release the first book until after I’ve completed the AI draft of the third book, so that way I can release all of the books in the first trilogy within 1-3 months of each other. And after the first trilogy is complete, I’ll market it as a trilogy while working on the last four books, probably releasing each of those a year apart, as I finish them.

The reason I’m thinking about this now is because a strategy like this is going to influence how I write all of these books. If I’m going to split the series into two trilogies, the last thing I want to do is end the first trilogy on a cliffhangar. It has to hold together as a complete story, with only one or two loose threads. But since I’m still in the early writing stages of the first book, I still have enough room creatively to make that kind of adjustment. I just have to decide if that’s truly the plan.

By the way, the first trilogy ends with the fantasy equivalent of the Battle of Mount Gilboa, where the Saul and Jonathan characters die in an epic battle and the David character becomes king (I know that in the Bible, there was a gap of several years between those two events, but I’m combining them for purposes of this book). So it is a rather natural stopping place, even if it does end on a massive downer, followed by a false victory (the second trilogy begins with David and Bathsheba).

Anyways, what do you think of this plan? Does it sound like a good idea, or is there a compelling reason I haven’t thought of yet for why I shouldn’t do it?