To provide some guidance for transitioning CEOs, McKinsey looked at the experiences of exceptional CEOs, those defined as the very top performers in the consultancy's data of about 600 chief executives at S&P 500 companies between 2004 and 2014.

Exceptional CEOs are also twice as likely to be hired from outside the company, inside hires must push much harder to change culture and inertia. Also pace is crucial. In hindsight, most leaders say they would have moved faster to build teams, change culture or address business opportunities in their tenure.

Still, 55 percent of the exceptional CEOs were internal hires. Clearly, insiders can move aggressively and achieve outstanding results. Doing so often means cultivating an outsider’s point of view to challenge the company’s culture with greater objectivity and overcome the organizational inertia that sometimes limits an insider’s span of action.

For any CEO starting a transition, there is much to learn from the best, suggest the consultants. Adopting an outsider’s view will yield the unbiased insights needed for breakthrough moves, they say. “Likewise, investing in a robust strategic review will provide a surer perspective for setting a strategic direction.” Being familiar with an organization’s context nevertheless will help calibrate the pace and extend of change.

Read more on McKinsey about Becoming CEO and What makes a CEO exceptional