of a population. You can make statements like, on average people are this size or treat certain situations this way, etc. But as soon as you attempt to assign that "average" to a group of individuals you will find that it probably won't work for a single person. I heard an example of this recently. Years ago the US Airforce took the average size of all pilots to standardize cockpits. The problem was that there were exactly 0 pilots that were the average size of all pilots. Their arm length, leg length, height, etc. were all uniquely different than the average. So this new cockpit didn't work for a single pilot.

IMHO, we can safely assume this is true when it comes to mental health. This is why parents are so important. They get to cater their parenting styles to their own kids, and even to each of their children individually. While certain parenting techniques may have better or worse outcomes on the average, if you were to take the average parenting style and use it for all kids it probably wouldn't have the desired outcome for any kids.

I think what is really at the root of your question is it worth the cost to try to eradicate all teen suicide. Since we haven't done so, there are only two possible answers: it's either impossible or it's not worth it to society. The answer is a mixture of both. It's not important enough to every single person to put in the effort and resources to attain a 100% effective reduction in teen suicide death, and even if it were the costs (money and loss of freedoms/rights) are so astronomically high that it becomes "not worth it."