Once again, I find myself compelled to use a bad example from a good book. Augustine's Confessions is a great book. You should read it. Don't judge it by this example.
Augustine tells the story of his saintly mother, Monica, and her upbringing. He has special praise for her very strict nurse, who would not allow Monica even drinks of water between meals, on the justification that if she became accustomed to satisfying her thirst with water as a child, she would satisfy it with wine as an adult and become an alcoholic. Augustine commends this severe instruction in temperance.
And then, in the very next paragraph, he admits that the young Monica, as soon as her parents gave her the chance to bring up the wine, started right in to sneaking drinks. She was cured of this habit, not by her nurse's admonitions, but because one of the young servant girls made fun of her for being a drunk. So much for careful training.
It seems that in Augustine's mind, obviously the training in temperance by not even drinking water *ought* to have worked, so it *did* work. That the mocking of the other girl actually had the effect demonstrates how God can use unlikely vessels, but it seems to do nothing, in Augustine's mind, to detract from the virtue of the other training. Theory is remarkably resilient to contrary experience.
I laugh at this, but I'm sure I do the same thing. I'm sure I've heard other people do the same thing, many times. An instructive practice, if you know some older parents and their grown children, is to ask what the parents did about thus-and-so and THEN, out of earshot, ask the children how well it worked. The story seldom comes out quite the same. And there's probably some truth to both sides.
That's why I'm very wary of giving or receiving advice. (Not that I don't regularly succumb to the temptation.) It's very, very easy to pass on what we think should have worked, or even what we think worked, except that in fact it was something quite different that had the effect, something that seemed insignificant or obvious or that the parent never even knew about.
On the positive side, most of us turn out tolerably well despite our parent's hare-brained theories, so our children will probably survive ours.