There is no single schedule that works for every book.
Promoting the same ebook periodically can introduce it to readers who did not see or act on an earlier promotion. This can be particularly useful for books in a series or titles that remain permanently free.
However, repeating promotions too frequently may produce diminishing returns because some of the same readers may already know the book.
When deciding how often to promote, consider your genre, previous results, whether your audience is continuing to grow, and whether anything about the book or series has changed since the previous promotion.
We currently recommend at least one month between free ebook promotions and three months between bargain ebook promotions.