Principle #3: Assume variability; preserve options
Generate alternative system-level designs and subsystem concepts. Rather than try to pick an early winner, aggressively eliminate alternatives. The designs that survive are your most robust alternatives.
—Allen C. Ward
System developers are inclined to try to reduce variability. That’s just human nature. It seems that the more you think you know and have already decided, the further along you think you are. In reality, though, that’s often not the case.
While it’s true that variability can lead to bad outcomes, the opposite case can also be true.
Variability is inherently neither bad nor good. ...