I think there is no "single" most important strategy in parenting, as well as in other relationships. As much as we aim to restrain ourselves, life is not perfect, and sh**t happens. And we are not perfect. and we can, and do lose it, sometimes, even if we try not to. I think this is what Dr. Kennedy meant, - not that yell and repair is a single good strategy, but the strategy is to aim, and being able to repair after things fell between the cracks. Of course restrain is a lot better than repair after losing it, but if it did happen, it is so much better to say sorry, I was wrong, and try to mend it than just pretend that noting happened...