Answer:
Looking at it from the information in the Question, I would say it is most useful during the "Selection Stage".
Step-by-step explanation:
I say its important during the selection stage, where the company select and subsequently hire suitable people for the job.
But remember this, Identifying intrinsic motivation, Work style, identifying ability to close sales and how they build customer relationships is extremely difficult.
Some of these traits are only visible when the selected employees begin to work! Although if the employees have had experience in the past, you can easily identify them. Just gotta look at their track record.