Ancient Sparta had no city walls:- I do not know why, but I like to think that it was a deliberate policy: A rejection of false comforts.
Static defensive positions can be useful, but only when coupled with a mobile army to disrupt the enemy's plans. On their own, all they can possibly do is postpone the inevitable. Of course, human nature being what it is, the appearance of safety that the city walls create soon leads to the withering of the real guarantor of safety: the army.
In software development too, we are surrounded by false comforts. We expend tremendous effort delaying integration and deployment, not touching legacy code "because it works" and so on, We should think hard about the procedures and tools that we use. Which ones give the appearance of safety, but in actuality provide only a false sense of comfort, and lead to a withering and neglect of the skills and tools that we really need to rely upon in a crisis?