The Production team can assign Departmental Timecard approvers ('Controllers'), in Settings > Admin.
Department Controllers don't have to be assigned if the Project don't want. e.g. they may not be needed for a small department like Sound or Script Supervisor.
Department Controllers can also write ('Generate') Timecards for their department, as well as approve Timecards. A person doesn't need to be a Department Controller AND a Department Admin - the Controller can do everything the Admin can. The Admin just can't approve.