After my first disfellowshipping I wrote my letters to the elders at 2 months, 4 months, and 6 months. I was denied in my 2 month and 4 month meetings. In my last letter I stated how repentant I was and all that stuff and alos related the corinthian disfellowshipping where the guy was sleeping with his step-mom after his father died and how he was reinstated within 6 months according to the chronology in the NWT Bible. I Got reinstated with my 6 month letter.
After my second disfellowshipping I didn't even write a letter until almost a year after I'd been going. The commitee that met with me were asses and told me that they didn't know if I'd ever do enough to return. They really didn't like me. I was going to another congregation but I still had to meet with the original commitee that disfellowshipped me 4 years before and a commitee at my current hall everytime I wrote a letter.
After that first year I decided on an annoyance tactic. I started writing a letter to the commitee every month and a half. They had to hold a meeting with me everytime and if they hadn't called to schedule a meeting after one week of me sending the letter I'd call the head elder of my commitee and bug him about setting a time to meet with me. It took awhile, but they finally gave in and reinstated me around the two year mark.
All in all, it was a big waste of time. I stopped attending meetings about 6 months after being reinstated the second time. I was never disfellowshipped for having doubts, but being disfellowshipped and seeing the way I was treated sure helped any doubts I had to grow until I finally knew that it wasn't the truth. So I send a thank you to the elders that disfellowshipped me. If it weren't for those guys I'd probably be an elder instead of a happy, holiday celebrating, college educated guy married to a beautiful worldly girl who has lots of free time on my Tuesday and Thursday nights and Sunday mornings. :)