Human Nature
Human nature is a funny thing. When someone makes a mistake in the heat of the moment, you would think that the passage of time would give them an opportunity to reflect on that mistake and see it for what it is. You would therefore expect that the passage of time would increase the chance that they might recognize and correct such a mistake.
But human nature doesn't work that way. The longer a person is able to keep from admitting their mistakes, the more time they have to build a bulwark of justifications supporting their actions. They may recognize the factual error in their causes, but even then they will still try to justify their actions through some other means: "Okay, maybe he wasn't guilty this time, but this punishment makes up for all the times he got away with it!".
So once someone makes a mistake, they tend to get less rational with the passage of time rather than more rational.
This is probably not news to anyone who's studied human behavior, but it's good to be reminded of this effect when asking anyone to correct any mistake that they've allowed to stand for a long period of time.