Well, the more people help, the less time it takes
I wouldn't say there is an usual rate, especially these days as people jump in the middle of whatever event they feel like and transcribe a few interesting questions. It's not a bad thing, but it makes it difficult to evaluate how long it'll take us to get done, as we might be looking at 70% completion of one event, 40% of another, 100% of a third, and 10% of a fourth - where previously we worked through them more or less sequentially.