It seems to me, not very often. An external rescuer seems to be the catalyst for overthrowing a tyrannical government or dictator. The slaves of Haiti were able to become free on their own, but the slaves in other countries didn't rise up successfully and obtain their freedom under their own power. Hitler and his facist cohorts were defeated in war, not by it's cowed citizens.
Had it not been for constant Western external pressure against Russian Communism, it's subjugated citizens would likely still be ruled by a totalitarian government. History leads me to believe that JWs will be unable to throw off their WT overlords on their own. It's rather silly, as no one is keeping them from walking out of the KH. Apparently, they are mental hostages who just can't see the big EXIT sign and leave the building.
Fear of shunning, i.e, the social death sentence, is the power that keeps JWs imprisoned. The GB wants to employ extreme shunning against ex-JW family again, which tells me they are losing too many JWs through communication with their ex-JW relatives.
The Internet is the only real external enemy that the WT has to deal with and they will have the plug pulled on all WT expose' sites that give them a legal opportunity to do so.