In my opinion, most people are too afraid of making mistakes, of somehow "looking bad". School and work promotes such fears every day: At school, pupils are expected to simply regurgitate what other people discovered through trial-and-error themselves, and to avoid attempting to create alternative answers themselves. At work, workers are expected to keep in line and bow their heads, as anything else is risky and rarely worth the potential trouble, especially for cross-cutting concerns.
How costly is the mistake? If it's endurable and don't affect you too much - both psychologically and financially, it's GOOD to recognize a mistake and correct it. In fact, being able to rapidly recognize and fix your mistakes is paramount, as I doubt anybody will be able to create a viable system without it. So be honest, ie. with yourself, otherwise one gets stuck in far-fetched fantasies of making millions or being able to make perfect designs/processes up-front, which is not realistic at all.
