They seem to try to swarm the thread for the first 100 or so posts. I believe the reason for that is to clutter the thread so any newbies who show up will be revolted by the arguing, or give up reading for lack of relevant info. After 100 posts or so, they usually leave.
The only other time I’ve noticed them in large numbers is when there is a BIG event. (BOOM!) It doesn’t have to be directly connected to a Q post. Just something that sends them into a panic.
We are only a couple months shy of a year. When will they stop? Rhetorical!