Every year, in virtually all large and midsize companies, high-level leaders come together for a leadership summit.

These events usually last two to four days and can rack up millions of dollars in costs: airfare and accommodations for the 50 to 500 or so attendees, fees for outside speakers, production expenses, the many person-days that go into planning, and the enormous opportunity cost incurred by taking so many top managers away from their normal duties for several days.

When executed well, these meetings are certainly worth the time and expense. They can serve as a powerful catalyst to align leaders, develop solutions to problems, introduce new strategies, and fuel collaboration across the organization. But many companies squander this rare opportunity to harness the collective knowledge of their frontline leaders.

The typical summit begins with a numbing sequence of platform presentations from a parade of C-level executives. Later sessions address topics, such as a new ad campaign or a product rollout schedule, that concern only a portion of the people in the room. A motivational speaker adds a dollop of entertainment. Some breakout sessions and an open-mic Q&A with the top team, emceed by the CEO, pass for an exchange of ideas.

Information, proposals, and solutions flow in only one direction—from the top down—and not all that coherently. Attendees leave only slightly better informed and better networked than when they arrived. It’s usually not clear whether they’ve understood the messages they’re supposed to take back to their people, much less what anyone would be expected to do as a result. A huge opportunity has been missed.