If your story gets too long, you might want to consider breaking it into more than one book. Reader attention spans are short these days. They may be put-off by a story that will take weeks to complete.
Another angle is that you might make more money in the long run with two shorter books than one long one. Many people have personal limits on how much they’ll spend on a book, regardless of length. Perhaps the best way to optimize your income is to break it down.
I’m current wrestling with this dilemma myself. I’m up to close to 120k words in my WIP and am not entirely sure how long it will ultimately be since it’s not yet close to being finished. I’ll finish it before I decide since if it really goes on for a while, it might even be best to break it into three instead of one huge doorstop-type novel.
What’s your opinion as a reader? Do you appreciate a meaty tome that keeps you engaged for weeks or prefer one you can finish in a matter of a few days? Are you willing to pay a bit more for a long novel when you know the author puts out quality stories?