You can probably guess the nature of the group from the other comments. Doing things like setting a rigid agenda would require me to be more prepared than I generally am, and would ruin the meeting's flexibility. On the other hand, there's one regular attendee who's clearly not of the hive mind. Usually even if that person starts going off, we can get through everything we need to in an hour.

So the problem is typically "move the meeting along", but it's more an irritation than a necessity. It doesn't feel like it justifies Process (TM), and that would ruin the warm-fluffiness for the rest of us.