John W. Rogers Jr., the chairman, c0-CEO and chief investment officer of Ariel Investments, has decades of experience serving in boards, including McDonald’s, Nike and The New York Times Company. He shared compelling insights about how to be an effective director and building cultures of diversity with me and David Reimer, the CEO of Merryck & Co. Americas, an executive mentoring firm.

Reimer: What have been the key lessons you’ve learned about how to be an effective director?

Rogers: Directors should focus on the areas that they know well. Warren Buffett often says you want to stay within your circle of competence, and you make better decisions when you’re in your circle of competence. Because of all the pressure on boards now, I’ve noticed that more directors can feel like they want to boil the ocean and get into all kinds of minutiae about everything that may or may not be important or relevant.

I’m a big believer in focus. Good directors understand how and where they can add the most value. For me, I focus on governance; diversity and inclusion, and, because I’m an investment professional, helping them think about their 401(k) plans, their pension plans, how to interact with Wall Street, and how not to get too swept up in whatever the current short-term Wall Street thinking is.

Reimer: Other lessons about what makes for effective board dynamics?

Rogers: I’ve found that when you have strong independent people around you, they’re going to make you better. But it’s also important to get people who know how to work well with each other. It’s like any great team – if you get the wrong kind of people together, they don’t win. It doesn’t matter how talented they are.