One poor performance does not cancel a reliable pattern.

A single bad performance is a data point in a set, and the set is what tells the truth about you. But bad days are vivid and ordinary good days are forgettable, so one poor showing feels more representative than the fifty competent ones behind it. That is a trick of memory, not a verdict.

When a bad one lands, deliberately count the others. Not to talk yourself out of the disappointment, only to put it at its real size. Then look for what was specific to that day, since that is where anything useful will be.