I think that the answer to the OP is that the trigger that awakens people is almost, if ever, logic.
The reason is that logical thinking has itself been subverted by JW conditioning. After all, if it was simply a matter of assembling and assessing the facts, then there would be no JW followers. None.
If you accept the premises that the world is full of evil people and that anyone who speaks against the JW organisation is an apostate who only tells lies. If you accept that the GB are, at the same time, fallible humans and yet divinely directed\inspired, then it doesn't matter how rational, intelligent or logical you are. In fact! These attributes will work against you as you will use those abilities to defend and reinforce your beliefs.
The factors involved in a trigger that awakens people are complex and almost random. Take the child abuse scandal for example. In theory that should be enough to awaken 100% of JW's. But a percentage of those on hearing about the child abuse scandal will "Wait on Jehovah", a percentage won't believe it at all and some will even not have heard about it at all. Of those that would be woken up, some will remain JW's through fear of losing their family, some through fear of death at Armageddon and so on. It's a minor miracle when all the factors align for a single person to wake them up.