Do you think all the GA's gather together to discuss their next con move? Or do you think Tommy just does whatever the hell he wants, stating it was a "revelation"?
I've heard that they indeed meet, and that there is (gasp!) occasional disagreement and discussion! The codgers hash it out and get all kinds of inspiration because they are all prophets, of course, and commune with Jehovah daily. Eventually, any point of disagreement is resolved by the power of the Holy Spirit. (tm)
There are the famous Thursday meetings of the Q12 in the temple, complete with milk chocolates for the senior members. Other than that, there are bigger meetings where the First Presidency and apostles hand out clues to the lesser GAs about what has already been decided.
Hafen was at a stake conference here maybe 5 years ago, and he mentioned that he would be in a meeting at the Salt Lake temple that evening. The kind of meeting where Hinckley used to bitterly chew them out for not meeting their goals or quotas. (My description, not Hafen's.)
Now whether the FP and Q12 hold joint meetings very often, I don't know.