Customers rightfully expect the undivided attention and resources of businesses that compete to serve their needs. So it is vitally important to be clear about who is—and who is not—a customer…Choosing a primary customer is a make‐or‐break decision. Why? Because it should determine how you allocate resources. The idea is simple: Allocate all possible resources to meet and exceed your primary customer’s needs.
(Robert Simons, Seven Strategy Questions, Harvard Business School Press, 2010)