What each person's breaking point turns out to be is highly personal. I think this is because the system is so intrinsically built up such that public questioning and exploration of doubts is completely forbidden, it results in everyone's doubts being isolated from each other, and since they develop in isolation there can be a enormous amount of variation. What works for one person won't even phase another. That's why it's important to have lots of people doing lots of different things to try to wake people up.
That said, I do think that there are methods that are almost certainly not helpful to anyone, or at the very least they reinforce the cult beliefs in more JWs than they actually have a chance of waking up. Aggressive protesting of conventions or extremely confrontational encounters at carts or at the door are likely among these, in my opinion.