I'm just about to start writing a new series. Unlike some of my others, this one is open-ended, rather than coming to a natural (if extensible) close after just a few books.
Is it better to release the new series books one at a time as they're finished, or to write the first several, and then release them quickly, one right after another?
Easy to say — hard to analyze. Lots of uncertainty.
For my own curiosity, I built a spreadsheet to help me do the analysis, and I'm sharing that here with you. As always, I am not responsible for any errors in my assumptions or algorithms — please do your own calculations using your own assumptions.
Time to write a book in the series: 3 months. That's 4 books/year. Sometimes it might be faster, sometimes slower.
I assume my partners (cover artist, conlanger) can keep up. That should only be an issue as the release schedule begins to crowd the writing schedule.
Length of series: Even if I write ahead, the various models end up the same beginning with book 10, so 10 books is enough for this evaluation.
To analyze, you need numbers. Those numbers have enormous uncertainty associated with them. Tinkering with the parameters will give you an idea about the sensitivity of the results to the initial setting. Since I'm only interested in the comparative results of different plans, using the same parameters will help cancel out the uncertainty.