Final answer:
Unstructured problem-solving skills are the least important for auditors in reviewing target processes for a complex consulting engagement involving banking organizations.
Step-by-step explanation:
The least important skill for auditors to possess in assisting in the review of target processes for a complex consulting engagement involving the consolidation of two large banking organizations is unstructured problem-solving skills. While this skill can be beneficial in certain situations, the auditors' primary focus should be on their ability to quickly develop relationships with the stakeholders, apply specific business-related skills related to the processes being re-engineered, and have experience in performing testing of controls.