I’m convinced that 1 of 100 babies sleeps miraculously, magically, the true sleep of the just, right out of the box. Some lucky parents of those genetic freaks think, “Our sleep technique works! We should write a book!”

In our case(s), it was something that required conscious effort. And when we did that... it worked. It honestly didn't seem like it would at first, but then it does.

Again, n=2 for me personally but as I mentioned in my reply to another comment we also had a friend with a "baby who won't sleep" and when they tried it also worked for them.

I don't make a habit of recommending this to people unless I'm close with them, bc I know that some people may take it personally or believe they are an exception. And I'd bet money that there are plenty of exceptions. But I also think they're exceptions rather than the rule. Whenever I've seen parents who believe that their baby can sleep through the night and work towards that goal, they seem to get there pretty quickly.

Edit to add: To put it in engineering terms, I think part of the problem is that you have to escape a local maximum of baby sleep. You may suffer several nights (possibly a couple weeks) that are worse than what you're used to in order to get to a place that's significantly better than what you're used to. When you're already sleep deprived, that can feel like a big hump to get over.