The PRIMARY purpose for continuous monitoring of security controls is to ensure:

The primary purpose for continuous monitoring of security controls is to ensure the effectiveness of controls. This involves regularly assessing the controls to ensure that they are meeting their intended objectives, and that any potential weaknesses are identified and addressed. Continuous monitoring also helps to ensure that control gaps are minimized, and that systems are available and aligned with compliance requirements.

The primary purpose of continuous monitoring of security controls is to ensure that the controls are operating effectively and providing adequate protection for the information assets. Continuous monitoring can also help to identify control gaps, ensure system availability, and support compliance requirements, but these are secondary benefits12 References = 1: SP 800-137, Information Security Continuous Monitoring (ISCM) for Federal Information Systems and Organizations, page 1-12: A Practical Approach to Continuous Control Monitoring, ISACA Journal, Volume 2, 2015, page 1.