Although digitization has made the printing and typesetting process much faster, distribution still takes time, especially in a country as big as America. (In Britain, with its smaller size and more insular literary culture, things move faster.) But once a book hits the market, the product has to move. “For all the weeks and months that go into the gestation of the book, we’re up against the so-called lettuce test once we get into the stores,” Kirshbaum said. “If we don’t get sales fast, the book wilts.”

Some stores like Target and Wal-Mart reserve room in advance for mass-market paperbacks by authors like Janet Evanovich or Nora Roberts. If an author is late with a deadline and misses the target publication date, the stores won’t have room on the shelf, since they’re expecting next month’s crop of projected best sellers. “Unless you have a major author, you probably have to wait another four to six months to publish that book,” said Matthew Shear, the publisher of St. Martin’s Press, which puts out Evanovich’s Stephanie Plum mysteries.

Like movie studios jockeying over opening dates to score huge first-weekend box office numbers, publishers often change publication dates to avoid competition for reader attention and marketing buzz. The publishers of Stephen King, John Grisham and James Patterson don’t want their books appearing at the same time, since all three hope to make No. 1 on the best-seller list.

Last year, Little, Brown & Company moved up the publication date of “Her Way,” a biography of Hillary Rodham Clinton by Don Van Natta Jr., a New York Times reporter, and Jeff Gerth, a former Times reporter, so it would appear around the same time as “A Woman in Charge,” by Carl Bernstein, published by Knopf. The Bernstein book sold more copies, though perhaps not as many as it would have without a rival book on the market. “You’re competing for retail space, you’re competing for bandwidth, you’re competing for column inches,” said Paul Bogaards, the director of publicity at Knopf. “Both books wind up suffering because readers have to make a choice.”

The same thing happened last year when two books on sushi  “The Sushi Economy,” by Sasha Issenberg (Gotham), and “The Zen of Fish,” by Trevor Corson (HarperCollins)  appeared nearly simultaneously. “You never want to get in a horse race with another book on the same subject,” said William Shinker, the president and publisher of Gotham.

Real-world events  the 9/11 attacks, the death of the pope, Hurricane Katrina  can either distract from books or provide a hook. This year, publishers are scheduling a range of titles to coincide with the Beijing Olympics, including “The Last Days of Old Beijing,” by Michael Meyer (Walker), about the destruction of old neighborhoods to make way for the Olympics, and “Wolf Totem” (Penguin Press), a novel by Jiang Rong that just won the Man Asia Literary Prize.