Assign an accountable owner who can explain how each necessary control operates, which records support it, and what happens when it fails. Tie ownership to the team that runs the control, such as identity, infrastructure, engineering, HR, facilities, procurement, legal, risk, security operations, or the relevant service owner.
Effectiveness checks should test whether the control achieves its intended result, not merely whether a document exists. Clause 9.1 requires the organization to decide what to monitor and measure, the methods, timing, responsibilities, and analysis, and to retain evidence of results. It does not require the same test or frequency for every control.