The concept of span of control was popularized in 1922 by Sir Ian Hamilton, a British general who said the experiences of centuries of military leaders have shown that a leader can directly control no more than three to six persons. A dozen years later, Lithuanian management consultant V.A. Graicunas introduced the idea that the relationships among people you supervise are as important as their sheer number. Supervising three people who interact daily, for instance, might be harder than supervising six who rarely cross paths. Graicunas devised a set of mathematical formulas for calculating effective span of control and said that, generally, an executive should supervise no more than four or five people.
Your employees are people, too! Read Manage Your Employees Better to get a firm grip on supervision.
The rule of thumb that an executive should supervise three to six people directly held up fairly well against challenges from efficiency experts, team-building zealots, technology buffs, empowerment boosters, megalomaniacs and others determined to increase the accepted span of control. Under the impact of reengineer-ing, however, some people claim that an acceptable span of control can include 10 people or more. And some claim that managers in flat, reengi-neered organizations can supervise up to 40 people.
In practice, you don't have to be an expert or a zealot to know if you're violating span of control. First, use the rule of thumb: If you have more than half a dozen people reporting to you, it could be too many. And the larger the organization, the fewer people should report to the CEO. Hamilton said generals should have no more than three direct reports, while low-level officers can handle as many as six.
Bear in mind that even six may be too many if the people directly under the manager have many dealings with each other. The reason is that, in addition to managing relationships with each subordinate, managers have to get involved to some degree in the subordinates' relationships with each other. Graicunas figured this meant that going from four to five direct reports, each with four direct reports of their own, doubles your effective work-load while increasing your working capacity by only 20 percent.
If the people you supervise don't interact, you can handle more of them. One management writer found that Sears Roebuck & Co. purchasing managers could each cope with up to 100 buyers because the buyers had specific responsibilities and rarely interacted.
If the calculations are too much for you, just take a look at the amount of hours you're working. When workdays for the people at the top are twice what they are for others, span of control is out of whack. Says Jauch, "A key sign is [when managers are] putting in 18 hours per day because they're trying to do everything."