In-house or Agency?

I believe in the Intersection Theory proposed by Frans Johansson in his book The Medici Effect. The intersection is the convergence of two industries and the resulting multitude of ideas that can be formed by combining the knowledge of both fields.
An agency seems like an ideal setting to discover the intersection. There are advertising executives working with clients from diverse industries. Combine the knowledge of the two parties and the odds of reaching the intersection are much greater than that of a group of employees in an in-house setting, where the day-to-day revolves around the product and/or service of that company.
In-house does have one benefit over an agency because it offers a work environment in which every employee can engage in a brand and understand the culture around that brand.
I’ve experienced working in both settings and believe that the agency setting better aligns with my goals, but the experiences learned in an in-house setting were invaluable.
To better understand which environment would work best for yourself I would say delve into each and determine for yourself the pros and cons. I would not have formed this decision had I not experienced both settings.