What we see in both software development and military operations is a tendency for the pendulum to swing back and forth between extremes. Yet in most cases, we need a balance between armor and discipline and between mobility and agility. Actually, though, I would say that the leaders in both the agile and plan-driven camps occupy various places in the responsible middle. It's only the over-enthusiastic followers who overinterpret discipline and agility to unhealthy degrees.

Tom DeMarco and Barry Boehm. "The agile methods fray." Computer 35.6 (2002): 90-92.