I found even as a PIMI that most jws I asked for specific things they heard or learned from the convention/meeting/talk, they would get that deer-in-the-headlights look and just say some general statement that could fit any WT event. Or worse yet, "it was all wonderful." They had no idea, nothing that stuck out in their minds.
Most JW's are there for the social network. Most are JW's simply because Mom & Dad are/were JW's and it's "that Old Time Religion" for them. Most JW's know NOTHING about what they believe.