“I did the best I could at the time.”
I see this as an understanding and compassionate way of talking to ourselves when we think of regrets or mistakes we’ve made. We can never have done better than how we did at the time with the particular variables involved (though we can learn from it and perhaps do better if a similar situation occurs again/in general in the future). Maybe we were tired, stressed, had wrong-view… there are numerous possibilities - and we couldn’t have done better because of these things.
Learning and growth happen throughout our lives, and perhaps we are even gaining wisdom for the next life too.
Both for ourselves and others I think this kind of self-talk is helpful, for many reasons e.g. you are what you do - “To become a harpist, play the harp” - Aristotle; people like to see other people happy and well in themselves.