Quality is value to some person - Gerald Weinberg

The Third Law of Consulting: Never forget they're paying you by the hour, not by the solution.

The principle is simple and powerful enough to be Marvin's Fourth Great Secret: If what they've been doing hasn't solved the problem, tell them to do something else.

Asking for efficiency and adaptability in the same program is like asking for a beautiful and modest wife. Although beauty and modesty have been known to occur in the same woman, we'll probably have to settle for one or the other. At least that's better than neither.