The third sentence:
I think “when something goes wrong” is when an error or mistake happens. You’re trying to learn prerequisites, if you make a mistake on that then you’ll make a mistake CF. That’s if CF uses that prerequisite.
When the quote above says this:
“often” means it’s gonna happen frequently. So frequently, when something goes wrong that’s gonna be a reminder to go back to prerequisites
I like how it says “good reminder” cuz it’s less about investigating about where to look and more about reviewing some prerequisites. Like, you don’t have to look too far to see if mistake is not caused by errors in prerequisites.
When the quote above says, “review and improve some prerequisites”, I don’t think I know too well what “review” means. I think you can look over some prerequisites and check quickly which you forgot about or what doesn’t make sense. You can then go back to that and improve it. I think it’ll most likely fix a mistake in higher level stuff.