Every one of my project plans ended with an expected failure and a plan to handle it.
When I joined EDS, my management was uncomfortable with it but let me keep it in the plan (If they forced it out, I would have found another job because I was working for idiots).
The customers and end-users loved it. They knew that they would not be abandoned at start-up.
Does your Project Plan include “Post-implementation Adjustments”?
It had better include them, or you WILL look sloppy or incompetent.
Also, if you want to force the principles in this article, hire a cat.