The first line of defense is accepting that the new system will fail, possibly in several ways. When I find myself thinking, “I must have this change because I can’t afford failures,” then I’m in big trouble. If I can’t afford some failures, a new system won’t help. And neither will an old one.

Nothing new ever works, but there’s always hope that this time will be different.

– Gerald M. Weinberg, The Secrets of Consulting, Chapter 9