Picture a pipe with three cracks in it — two are small, only one is large enough to let in a significant amount of water. Many would say, “fix the large crack, because it will be cheaper than fixing all of them, and it should stop the majority of intrusion.”

But after fixing only the large crack, you find that water is still getting in, and even worse, the two previously small cracks are deteriorating even faster than before.

Now scale that concept up to an entire...