A key, unspoken role of a marketing agency is to provide political cover for the in-house leader. The agency can act as the "voice of reason," holding the line on unpopular but necessary strategic changes and using their broad industry experience as justification, thus absorbing the internal friction.

Conny Kalcher was not looking to join an insurance company after 33 years at Lego. However, the Zurich CEO's inspiring vision for a customer-centric transformation presented a challenge so compelling that it overcame her initial hesitation about the industry's reputation.

Agencies are optimized for efficiency, stifling the creative experimentation needed for platforms like Meta. Top-performing brands employ an in-house strategist whose sole job is generating a high volume of diverse, "wacky" ad concepts—a function that can't be effectively outsourced.

Amazon's CCO explains that at an agency, creativity is the core product. In-house, it's just one business function among many. This requires a humbling shift from "selling" ideas to deeply understanding the business constraints and priorities that drive decisions, moving from being listened to, to being the listener.

Tim Hortons' CMO credits her time at an agency for teaching her how to be an effective client. By experiencing firsthand the impact of clear (or unclear) briefs and direction, she learned how to partner effectively with creative teams once she moved to the brand side.

GM's marketing leader reversed a trend of outsourcing key functions. He argued that relying too heavily on agencies underdeveloped internal skills, making the company slow and unaccountable. Bringing capabilities in-house, while challenging, was essential for transformation and agility.

New brand managers often change successful strategies just to put their personal stamp on the brand. A long-tenured agency partner can act as a vital custodian of brand equity, leveraging their deep institutional knowledge to push back against short-sighted, unnecessary changes and maintain consistency.

Brands that scale rapidly don't wait to upgrade talent. They either raise capital to hire senior, experienced operators from the start, or they achieve a similar result by partnering with best-in-class agencies and ruthlessly cycling out any who can't innovate and push boundaries.

Amoo-Gottfried considers leaving his prime role on the Nike account to launch an agency in Ghana his riskiest but most formative career move. The experience of building from scratch in a challenging environment fundamentally changed his capabilities as a leader and operator.