Ideally start with a Leadership MRI
Usually the senior leadership team wants to do this as a group. This might number 10-60 people depending on the size of the organisation.
We have found that the scores given by senior management are frequently about 15-20 points higher than down the line and also the patterns of their scores are not always aligned with the heart of the business.
But they do provide a good starting point.
Implement the MRI in a business unit that is important, is facing substantial change, where risks are thought to be high and payback for success is big or cost of failure is very large.