When should an IS auditor assess risk in the context of cross-training practices?

Assessing risk in the context of cross-training practices is most pertinent when considering the scenario where one person knows all parts of a system. This situation presents a significant risk because if that individual were to leave the organization, become unavailable, or make errors, there may be a lack of continuity or understanding among the remaining team members regarding that system.

Cross-training mitigates this risk by ensuring that knowledge and skills are distributed among multiple individuals, thereby creating a more resilient operational environment. If knowledge is concentrated in one person, it can lead to vulnerabilities in operations and an increased chance of disruptions.

In the other scenarios, while they highlight important aspects of workforce management and risk assessment, they do not emphasize the immediate risk associated with knowledge silos regarding the system's operation. Therefore, focusing on individuals possessing comprehensive knowledge of an entire system is crucial for identifying and managing risks effectively.