We tell our kids, if you did your best you have nothing to be ashamed of. That's true. But somewhere along the way, I did my best, became an excuse. Excuses stop us from moving forward. They stop us from having the life we want. They are an easy out. We say "I did my best" when the truth is "I'm too lazy to try harder."
Be careful of these easy phases like "Time is more important than money" and "I did my best." They hold a kernel of truth, but all too often we use these cliches to justify non-productive behavior.
Instead, to get the life we want, we have to examine what went wrong. We have to be honest with ourselves and willing to the hard work necessary to resolve issues in our lives. She could have studied an extra hour instead of playing Minecraft, or had us quiz her. She could have taken an extra moment to check her room before calling the job done. She could have taken a deep breath instead of yelling at her sister.
Watch your language and internal dialog for cliches and ask yourself - are you making an excuse? It's much easier to use an excuse and forget about the outcome. But when we do that, we are doomed to repeat the behavior. We'll be stuck in a loop resulting in outcomes we don't like. Replace that with examining our past behavior honestly, and thinking about what you could have done to create the outcome you desired.