My perspective on this issue is perhaps limited by what I myself experienced that led to my leaving, that said:
For me, it was stuff that went on that affected me directly and personally, bad stuff that went on despite my "prayers" to "Jehovah" and a firm desire to do things "the organizational way"...ie....the so-called concept of "waiting on Jehovah".... Eventually it dawned on me (my awakening to the real "truth" if you will), that Jehovah's Witnesses DON'T have any special blessing from God.....and so on and so forth........
So, the "jolt" for me wasn't something that some other person purposefully planned, with the thought of "getting me out"..... Indeed, as others have said, I seriously doubt any kind of contrived "jolt" would have done the trick.
However, I think there is something to be said for Scully's "approach": Let your former associates know how things are going for you since you left....I've had limited opportunity to do that, but it seems a good approach to get around the usual JW group-think...
Another approach that may be useful is to figure out a way to get a Witness to examine the answer to this question: "What would the Organization have to do to convince you that they don't have God's specific blessing?" If they can even begin to ponder an answer, it's a start.
I don't consider myself a stupid or gullible person, either now or in the past, but with effort, I can understand why some here characterize those of us who stayed Witnesses for decades as in effect, stupid people who couldn't think. It is much more complicated than simply "not thinking", in my view. More of a betrayal of love and trust....afterall, the people you love and trust are not subject to the same skeptical thinking/analysis as would a stranger receive, at least not until they give you a reason to dig deeper........
My two cents,
---Dan