What is the maximum number of subordinates whom the manager or leader can supervise accurately and effectively?

Thanks

That depends on :

• Leader- Manager experience.
• Leader personality itself and capability.
• Organization size.
• Number of teams.
• Kind of team unified or not.
• Number of teamleaders.
• Orgnization structure.
• Organization policy.
• Type of managing.
• Type of business ( Indoor - Outdoor).
• Number of departments.
• Many other factors.

So in my opinion, I don't think there is a fix number to be managed accuratly and effectively.

Thanks for invitation,

Supporting Mr. Omar Saad's answer, which I believe more than enough.

Welcome Unlimited if used and processed in quantitative ways

Hello again , I think it depends on the capacity of each subordinate to take reponsabilities and also the nature of the work , if it is complex or not .

I have managed from one to 13 at one time, with numerous projects for each 

It ultimately relies on the manager and the system they are asked to operate in. Human beings can handle a finite amount of interactions per day, once exceeded their own inherent ability to comprehend and take action is reduced. This occurs in every company everyday at every level. 

Quality over quantity but allowing a single leader to take on ever larger numbers of subordinates he/she must have complete support from the direct report enabling changes which create efficiencies to the management system. If you as the direct report create a burdensome system of paperwork, meetings and silly requests the ability for a manager to oversee large numbers of personnel is greatly diminished. 

thanks for the invite.  for me, there is no maximum or a minimum number of subordinates a manager should handle. it is the average.  but that average comes from the result of identifying the number of transactions, the scope, time, budget, risk, quality, culture and the objective set by the management. since you aim for quality not quantity alone, the manager has to manage, not control the complexity of having less or more subordinates.   

Thank you for the invitation.

Managing People.

Managing people can be rewarding, and it's also an extremely important role in most organisations. Research has shown that the first tier of line management (front line managers, supervisors and team leaders) have the greatest influence on staff performance and engagement to their organisation.   A supervisor, when the meaning sought is similar to foreman, foreperson, overseer, cell coach, manager, facilitator, monitor, or area coordinator, is the job title of a low level management position that is primarily based on authority over a worker or charge of a workplace. A Supervisor can also be one of the most senior in the company.

Many centers today have between8 and staff per supervisor. ... And technical support centers and other complex environments can have as few as five staff per supervisor. ... In many cases, team leaders are assuming functions that traditionally have been in the domain of managers and supervisors.

Typically a manager or Commercial Director supervises his departmental staff, example our company  (GMMOS LLC marine based in Dubai(U.A.E.) had employees in inventory and Commercial department.  He had the role to play for other duties of the company hence a maximum of to people can be the magic number.   We had a Galagher Cranes Dubai LLC(overhead) and he managed the staff for the sister company.   In my  directorate, Hospital department, we had8 staff and I had to delegate to the8 of them (routine task, typing, letters. Working with information to be sent for medicals and housing (new staff and students joining the university, meetings, filing in the directorate), important files updated for the His Highness the President, memos to the7 departments under the directorate and5 colleges our director managed and reported to the HH The President.  Each of us completed one or two task under supervision.