Span of control
Span of control refers to the number of individuals that can be directed by a single manager. It also refers to the number of concepts of which the average person can keep in active thought and "multitask"
Classic management theory, especially before Peter Drucker, assumed that a manager could manage approximately five subordinates. Drucker, however, suggested that when the people managed were knowledge workers, they were more self-directing and a broader span of control would work.
The Incident Command System (ICS), which is the standard paradigm for operational management of disaster situations (e.g., fire and rescue) assumes a span of control of five, with specific mechanisms for creating additional management levels when spans of control become too wide. It must be remembered that ICS is intended for situations in which the situation can change radically in short minutes.
Matrix management is yet another complexity, where an individual may have a "home" administrative manager, but report to several task managers.
Military organizations, since serious thought was given to command and control, also tend to use the model of five direct reports. A related hierarchical rule of thumb has been that a commander's map shows the units one level above and two levels below his place in the hierarchy, but that he should issue commands only to direct reports.
Again, knowledge emphasis may change this. In network-centric warfare, commanders, as well as operators, have tools to help them maintain situational awareness. It is now considered quite desirable that a given level not only track one level above and two levels below, but also to track peer organizations. In battle, knowing where one's neighboring units are and what they are doing, especially if they exploit sudden opportunities outside their assigned geographic area, has become critical to prevent fratricide. Another complexity of military span of control reflects the need for fault tolerance: if a commander or headquarters is disabled or cut off from communications, it must be predefined who takes over the missing leadership function.
Both in business