When determining the level of staff and resources for an assurance engagement, the most relevant factor for the chief audit executive (CAE) is the availability of resources with the specific skill set required for that particular engagement. This is because assurance engagements often involve complex and specialized areas that necessitate specific expertise to effectively evaluate controls, risks, and processes.
IIA Reference:
IIA Standard 2230: Engagement Resource Allocation states that internal auditors must determine appropriate and sufficient resources to achieve engagement objectives based on an evaluation of the nature and complexity of each engagement, time constraints, and available resources. The emphasis is on ensuring that the team assigned to the engagement possesses the necessary skills and knowledge.
The Practice Advisory 2230-1 further suggests that the CAE should consider the complexity and risks associated with the engagement and ensure that the assigned team has the appropriate experience and technical skills.