I do believe some babies do it without prompting.
I agree with this! I starting actively trying to teach my first son because I wasn't coping at that point. I used a no-cry technique I developed from "the no-cry sleep solution" and it worked well- took at least a month to get there.

I've been more relaxed second time around but I am helping my son see that he can self settle by allowing him to go down to bed awake sometimes and going in to him as he needs it.