I think some on this site have commented that the Witnesses as a religion seem quite different now than some years ago. There has been changes I believe over the years. These changes may continue until it reaches a point that I may feel differently about the preaching work.
I know the thread will be derailed anyway, so I will try to stick to the main point and address that comment.
Why do some go back? There are some, like the one I quote above, who must feel that the Watchtower and it's leaders are the closest thing to "the truth" and just need some adjustments. They just don't consider enough how the Watchtower has NEVER EVER EVER been correct about any of their doctrine that are unique to them. NEVER!!!!!!! They just don't think enough about how Watchtower leaders demand total obedience or else members are shunned. Maybe they lack social skills and don't want to try to fit in anywhere but would rather suffer the shunning in order to be totally accepted back into the fold in a few months.
I suppose that if you are done with education, and don't care to share birthday cake with coworkers, and are prepared to either give up your free time or else have your friends and elders criticize you for not doing so, then you may be ready to start examining the doctrine itself before returning.
I don't expect such a person to listen to the likes of me, as I have seen the light about all of Bible-based belief, but even if a person still wanted to worship the God of the Protestant or Jewish Bible, they could do better to go without organized religion or find some nondenominational group. Deciding on a percentage of correctness just seems silly to me. Either your religion lets you believe what you want without shunning or ostracizing you, or who needs it?