(FORTUNE Magazine) – BankAmerica has a new CEO. So do the Times Mirror Co., Host Marriott, CompuServe, and ad agency N.W. Ayer & Partners, to name just a few. Robert Lowes, Burger King's new boss, is the company's third in six years. At California clothing maker Esprit de Corp., David Folkman, the fourth CEO in five years, stepped down in July. Another search party has been summoned. An Esprit de Corp. spokesperson, apparently hoping for a break from recent tradition, says: "Speed is not the main criterion here. We're really hoping to find the right person."

If the revolving door at the top of U.S. corporations seems to be spinning so fast that it's just a blur of pinstripes, you're not imagining it. A new study, co-written by headhunting firm Paul Ray Berndtson and researchers at Cornell University, has tracked the career moves of more than 1,400 senior managers and found that 42% change jobs, either in-house or at a new company, every two years.

"What we're seeing is a 12-month honeymoon period, where executives experience high job satisfaction," observes John Boudreau, a professor at Cornell who is the study's main author. "After they begin to get involved in the nitty-gritty of the new position, that initial enthusiasm seems to fade." Then comes what Boudreau has dubbed "job hangover"-or, call back that headhunter pronto. How about lunch?

Such hopscotching will not necessarily bring happiness. Boudreau analyzed job satisfaction among the chronically restless and found that the thrill of the honeymoon decreases with each job change, while the hangover does not. A fickle heart can also do long-term career damage. Explains John Challenger of Challenger Gray & Christmas, a search firm in Chicago: "It's great to be perceived as someone who's always eager for new horizons, but after a while people do begin to wonder. Were you lousy at everything?"

Of course, every rule has its exceptions. Look at Richard Irvine, 54, newly named president of Mikohn Gaming, a fast-growing Las Vegas maker of games, lighting, and surveillance systems for casinos. Irvine, a participant in the study, seems to defy its findings. He's a career career-hopper: Along the way he's done two stints at Disney and a few years at Straight Arrow Publishing, best known as the folks who bring you Rolling Stone magazine. He's enjoyed the whole ride, but now he plans to stay put for a good while. Why? Simple: "Being president is better than being vice president." Ah. Memo to Cornell: Are promotions more fun than lateral moves? Here's a hint: Is Caesars Palace open on Sundays?

--Anne B. Fisher