Rocketman,
I agree that it depends on the congregation, as there are some that are better than others, but from personal experience, I thought that the cong. that I was attached to for most of my life were one of the better ones and it took 4 years for any elder to contact me, and that was because I had been speaking to my parents and given them some info which they then passed on to the Elders.
The elders that came to see me weren't even at the hall when I was there, so the elders that I knew and had a relationship with still have never bothered to contact me.
All it does is reinforce peoples doubts when they leave. I think if the elders did what they are supposed to do they could possibly prevent a lot of people leaving...lets hope they never figure this out!