Here’s the thing about adding even a single direct subordinate to be managed: It will affect the amount--and nature--of your work not linearly but geometrically. 

On the Harvard Business Review blog, Schaffer Consulting’s Ron Ashkenas cited a span-of-control study stating that when a manager goes from four to five subordinates, his potential interactions with them increase from 44 to 100 over a given period; and going from seven to eight subordinates raises the total interactions from 490 to 1,080.

Span of control is a classic business concept, but it made the news a couple of years back when the Air Force announced a restructuring. "The reduction of 18th Air Force’s span of control allows for greater focus on its mission to present operational flying air mobility forces to U.S. Transportation Command," said Lieutenant General Mark Ramsay, 18th Air Force commander, in a press release.

One day earlier, an HP VP named Iain Stephen used the term in The Register when explaining a decision to split the account management of HP's StorageWorks division.

As for the eternal question "What is the right span of control for a manager," a consultant named Jamie Flinchbaugh addressed it on his blog last year. "There is no right answer," he wrote. "Some factors to consider are: The narrower the span of control, the more coaching at the point of activity can be done; the broader the span of control, the more the entire process can be encompassed within fewer decision makers and more aligned decisions."

How many subordinates is too many? For more on the span-of-control concept, see the article "Are You Talking Too Much, or Does It Just Seem That Way?"

This article originally appeared on The Build Network.