Well, I tried looking it up, but can't find much in a pinch, but here is one reference: http://learnmem.cshlp.org/content/11/5/566.short
If you believe it, unlearning (extinction) does not remove the old learning, it covers it up with an extra layer of compensatory learning, while the original habits still lurk underneath. Which matches my experience tutoring students who learned a bad technique, or observing people (including myself) who learned a bad habit: even after a lot of effort it is really easy to slip up into them.
I'm not sure your reference is very conclusive on this topic: 'We argue that the question “is extinction reversal of acquisition or new inhibitory learning?” is therefore not well posed because the answer may depend on factors such as the brain system in question or the level of analysis considered.' Your personal experiences do make sense to me though. Reminds me of this for some reason.
Sometimes our minds suddenly "click" and we see a topic in a new light. Or sometimes we think we understand an idea, think it's stupid and ignore attempts to explain it ("yeah, I already know that"), until we suddenly realize that our understanding was wrong.
This kind of insight is supposedly hard to transmit, but it might be worth a try!
So, what kind of important and valuable insights do you wish you had earlier? Could you try to explain briefly what led to the insight, in a way that might help others get it?