Sometimes the best way to make a companywide change is to come down hard, fast, and with an attention-grabbing sense of drama. That's what Dropbox--the fast-growing cloud storage company--did when it battled the productivity and morale-sapping scourge of recurring meetings. The results were profound.

Unnecessary meetings plague most organizations. The Centre for Economics and Business reports that the average office worker sits in meetings about four hours a week and feels the majority of that time is wasted. At Dropbox, the problem was even worse: Some engineers were spending more than half their time in conference rooms. Employees complained that meetings were too numerous, too long, crowded with people who didn't belong there, and often pointless.

Dropbox's leaders responded with a battle cry: "Armeetingeddon has landed." That was the subject line on a companywide email that went out in August 2013. The message informed employees that all recurring meetings had been deleted from their calendars. "If you check your calendar, you'll notice that it's feeling a bit light--on midnight we flipped the switch," the note read. "Ahhh doesn't it feel fantastic?"

In their book Scaling Up Excellence, Stanford professors Bob Sutton and Huggy Rao explain that building an organization requires both addition and subtraction. As an organization scales, some of the rules, activities, and rituals that once made sense lose their rationale but hang on as relics. Weekly meetings are typical. Managers establish them for good reason. Years later that reason is gone thanks to changes in relationships, roles, and customer needs. The meetings, however, remain.

The purge at Dropbox exemplifies strategic subtraction in a company bent on scaling well. "We were bloated in terms of meetings," says Graham Abbott, Dropbox's office team lead. Armeetingeddon, he explained, was an exercise in prioritization. Afterward, employees had to consider each meeting individually--give each one some real thought--and decide (collectively with other attendees) whether to return it to their calendars. Employees viewed Armeetingeddon as a positive change and trusted the company to make their lives temporarily more difficult to improve efficiency in the long term. By doing so, they realized some meetings had outlived their purpose.

Dropbox reinforced the message by prohibiting meeting hosts from rescheduling recurring meetings for two weeks after Armeetingeddon. This wasn't just a request. Each night, any recurring meetings that had crept back onto the calendar were deleted. People often hesitate to cancel meetings to avoid damaging social relationships. Dropbox eliminated the awkwardness of having to say, "Let's not meet." Armeetingeddon "cleaned the slate in a way that employees didn't take personally," says Abbott. The only meetings that were spared were recruiting meetings, heads of staff meetings, and meetings involving an external stakeholder.

Armeetingeddon was intended to change everyone's behavior, including that of senior leaders. Minutes after the initial email went out, a follow-up urged team leaders to:

respect the "Sanctuary period" and avoid scheduling any recurring meetings for two weeks; make sure meetings have agendas, owners, and action items; encourage team members to be protective of their calendars; and consider a venue other than a conference room: "Go outside and get some vitamin D."

Two years later, Dropbox employs nearly three times as many people at its San Francisco headquarters, yet it has only approximately doubled the number of conference rooms. Until recently, the number of recurring meetings has not increased despite the company's growth. In the post-Armeetingeddon era, meetings are shorter and more productive, with less rambling discussion and more focus on making decisions. Dropbox now provides mantras to guide meeting etiquette and design. These mantras guide all meetings, not just recurring ones:

Be conservative with meeting invites--Invite only key stakeholders, not "spectators." A cap of three to five people is recommended for decision-making meetings.

Every meeting must have an owner--Cancel meetings that lack a clear owner who keeps it on track.

Schedule meetings if (and only if) other methods of communicating won't cut it--Consider whether another forum, such as email or a chat, can accomplish the same result.

The company's internal website advises employees invited to meetings to ask themselves, "Do I really need to be here?" People who go to a meeting and find their attendance is not required are encouraged to leave: "If you find yourself on your phone or laptop during a meeting, that's a good sign that you're neither deriving nor contributing value to the meeting and that it might be worth reconsidering."

Today, a conference room at Dropbox headquarters is named "Armeetingeddon" to commemorate that fateful day. Though initial victory has been secured, the enemy lives on. More recurring meetings have recently been popping up on employees' calendars. Abbott says that Armeetingeddon "will definitely be replicated." Dropbox will once again temporarily banish recurring meetings, with the exception of those types noted above.