This article originally appeared on LinkedIn.

Dilbert’s pointy-haired boss goes ballistic when challenged about the value of the day’s big meeting: “I called this meeting, and it’s not a meeting until someone’s time gets wasted!”

That’s not far from the truth, though the motivation for meetings at most large companies is usually more benign. A few years ago, a leading technology company saw its profitability and productivity declining. It surveyed 30,000 employees worldwide to determine how to improve organizational effectiveness. Employees responded that only 54 percent of the time spent in meetings was time well spent. They cited unclear meeting purpose, unnecessary standing meetings, overly long meetings and unnecessary attendees as reasons for unproductive meetings.

Too many people get together without really knowing why, simply because it was on their weekly schedules. Admit it, you’ve been there. You’ve probably called some of those meetings. I know I have.

What’s less obvious to people, however, is the ripple effect those unproductive meetings have on an organization, especially when top executives meet. My Bain colleague Michael Mankins and his team analyzed time use at one large company and found that people there spent 300,000 hours a year just supporting the weekly executive committee meeting. Using data-mining tools to analyze the Outlook schedules of everyone in the company, they found that the executive committee meeting required preparation and ancillary meetings by unit heads, senior advisers, teams ... and more teams. You get the point. The meeting prep radiates outward like a forest fire consuming widening circles of employees.

But meetings don’t have to get the best of you. You can manage them as closely as you manage every investment. Here are three things you can do:

Have a purpose. If you don’t know why you’re meeting, don’t meet! Most valuable meetings have one of three purposes: inform, discuss or decide. Before calling a meeting, think about whether you could inform people through a different medium, or use a tool to reach a decision. And take most standing meetings off your calendar, because they breed poor habits. If a meeting is truly the best alternative, be clear on its purpose and desired outcome.

Manage the invite list. In many companies, it’s bad form not to invite lots of people to a meeting. What people don’t realize is that every additional attendee adds cost and gets in the way. Remember the Rule of 7, which states that every attendee over a total of 7 reduces the likelihood of making a good, quick, executable decision by 10 percent. Once you hit 16 or 17 people, your potential for decision effectiveness is close to zero.

Don’t send delegates to meetings unless the purpose is solely to inform. Delegates are rarely empowered to actually do something, which means a “decision” meeting gets turned into a “discuss” meeting, which requires another decision meeting. If you can’t get the right people in the room, don’t have the meeting.

Change the default time. Not too long ago, most companies called 30-minute meetings. Now the typical default time has grown to 60 minutes, even though every additional minute generates a higher cost. How about a rule that says if a meeting lasts more than 90 minutes, it requires approval by an executive who is two levels above the convener?

A Bain colleague recounted recently how a U.S. undersecretary of defense in charge of procurement came to her first meeting with contractors and saw about 60 people in the room. She asked everyone to say who they were and why they were there. Participants rolled their eyes but did as she asked.

After the first two had identified themselves, the undersecretary said, “Thanks for your interest, but we won’t need you here. You can excuse yourself.” Others met a similar fate. By the time she got to the 10th person, others were getting up to leave, knowing they had no real reason to be there. Eventually the group comprised about 12 members — and the productivity of that meeting rose about fivefold.

Take a cue from this government leader. Once you do, your teams can focus on the most important issues, consider alternatives and make the best choices in the shortest amount of time.