Sometimes, we don't even know.
We were nearly done with Book Three, "Badge of the Desert Sage" when we felt like it needed a little kick. Jim came up with the idea of changing whodunnit. Granted, this new idea was a vast improvement and gave the book some much needed flavor, but it then required us to go back and rewrite substantial portions of the book.
The book is better-organized now and I like the plot a lot better than before. But it took us six weeks to write the book instead of the usual four. Ha ha! I know that six weeks to write a 80,000 word crime novel is still warp speed, but to us, it felt like the book was taking foreverrrr. (Never mind the fact we were slowed down by the New Year's holiday, several unexpected snow days, and a 10-day bout of pneumonia).
I am happy to announce it is finally finished and has moved into the second-round editing stage (which takes a couple of days). So, I am going to go out on a limb and say that Book Three will be published later this week.
Book Four is already incubating and has a killer-plot (and a couple of hilarious sub-plots). It's going to be a lot of fun. We hope you'll keep reading!