One of the annoying problems I remember repeating in all of the teams was that it is so easy for someone to hijack a discussion and in some cases make it unnecessarily long and exhausting. It’s hard to react to it sometimes, because initially it starts as a simple contribution leading to a point and only after some time you realize that someone has just turned it into an aimless brainstorming with involuntary audience.
I remember that in one of the past teams we were using a plush toy 
- whoever was holding the mouse was allowed to contribute to the discussion, whoever wanted to talk next, asked for a mouse first. I would say it did something, but obviously sometimes people just exploded and started talking with empty hands anyway.
Anyone encoutering some other simple hacks to easily prevent hijacks without having an explicit human moderator?