An article in the April, 2012 issue of the Harvard Business Review analyzes the change in the number of direct reports to corporate CEOs in the last twenty years. Apparently, the number has doubled from just under 5 to just under 10. The trend is not just at the CEO level, but at the layer directly under the CEO, too.
So, what exactly is the right number?
According to the HBR article, it depends on several factors: how long have you been in the position, how much cross-organization collaboration you have to do, how much time you spend focused outwardly as opposed to internal business, and for CEOs are you playing both the CEO and Chairman roles.
So, if you are newer in the role, oversee closely-related businesses, and your time is spent mostly on internal business you can manage twelve or more direct reports. Being new in the role may seem counter intuitive to a larger span of control, but what the authors research found is that a larger span for a new executive gets them more opportunities to learn the business and assess talent. The other factors are related to the use of your time.
In my experience, span of control has never been well thought out. When I started working. seven was the experts' number for the maximum span of control, but at one point I had twenty direct reports in my company's constant efforts to flatten for cost reduction purposes. Both of those numbers were fairly arbitrary, so having some well thought out gudelines makes sense. Ultimately, you need to find a number that supports your business well.