After reviewing several sources, the number appears to be on avg 9-10. I invite you to read the excerpt below related to considerations and sources referenced. Let me know if you have any more questions!

Optimal span of control

Three or four levels of reporting typically are sufficient for most organizations, while four to five are generally sufficient for all organizations but the largest organizations (Hattrup, 1993). This is consistent with ERC’s survey findings as well. Ideally in an organization, according to modern organizational experts is approximately 15 to 20 subordinates per supervisor or manager. However, some experts with a more traditional focus believe that 5-6 subordinates per supervisor or manager is ideal. In general, however, optimum span of control depends on various factors including:

• Organization size: The size of an organization is a great influencer. Larger organizations tend to have wider spans of control than smaller organizations.

• Nature of an organization: The culture of an organization can influence; a more relaxed, flexible culture is consistent with wider; while a hierarchical culture is consistent with narrow. It is important to consider the current and desired culture of the organization when determining.

• Nature of job: Routine and low complexity jobs/tasks require less supervision than jobs that are inherently complicated, loosely defined and require frequent decision making. Consider wider for jobs requiring less supervision and narrower for more complex and vague jobs.

• Skills and competencies of manager: More experienced supervisors or managers can generally be wider than less experienced supervisors. It’s best to also consider to what degree supervisors and managers are responsible for technical aspects of the job (non-managerial duties).

• Employees skills and abilities: Less experienced employees require more training, direction, and delegation (closer supervision, narrow); whereas more experienced employees requires less training, direction, and delegation (less supervision, wider).

• Type of interaction between supervisors and employees: More frequent interaction/supervision is characteristic of a narrower. Less interaction, such as supervisors primarily just answering questions and helping solve employee problems, is characteristic of a wider. The type of interaction you want your supervisors and managers to engage in with their employees should be consistent with the control they are given.

In addition, special consideration should be given to the direct reports of executive and senior management levels. Typically, the number of direct reports for these individuals are lower than supervisors and managers as too many direct reports at these levels can complicate communication and lengthen response time for crucial decisions.

Sources:

• Bell, R. R. & McLaughlin, F. S. (1977). Span of control in organizations. Industrial Management.

• Davison, B. (2003). Management span of control: how wide is too wide? Journal of Business Strategy.

• Gupta, A. (2010). Organization’s size and span of control. Practical Management: Transforming Theories into Practice.

• Hattrup, G. P. (1993). How to establish the proper span of control for managers. Industrial Management.

• Juneja, H. Span of control in an organization.