For years, it was a schedule as predictable as a calendar: novelists who specialized in mysteries, thrillers and romance would write one book a year, output that was considered not only sufficient, but productive.

But the e-book age has accelerated the metabolism of book publishing. Authors are now pulling the literary equivalent of a double shift, churning out short stories, novellas or even an extra full-length book each year.

They are trying to satisfy impatient readers who have become used to downloading any e-book they want at the touch of a button, and the publishers who are nudging them toward greater productivity in the belief that the more their authors’ names are out in public, the bigger stars they will become.

“It used to be that once a year was a big deal,” said Lisa Scottoline, a best-selling author of thrillers. “You could saturate the market. But today the culture is a great big hungry maw, and you have to feed it.”