Excellence means fewer excuses survive inspection.

As your standards rise, the reasons you used to accept start to look thin. Not enough time, the brief was unclear, someone else was late. All of them may be true and none of them changes the fact that the work is not good, and at a certain point you stop finding them satisfying. That dissatisfaction is what drives most improvement.

When you next explain a poor result, listen to whether you believe yourself. If not, ask what you could have controlled. There is almost always something, and it is usually earlier in the process than the explanation suggests.