Consensus meetings and performance reviews. I was a manager until recently and had to sit through quarterly consensus meetings to rank people in our organization (~90 people). These were extremely tedious, lasted HOURS, and could be contentious as everyone fought for the members on their team to have a better ranking. Ratings had to meet a distribution, which meant that it didn't matter how well someone performed at their core job, if they didn't have "extras" that helped to bump them up in the rankings, they would just get a mediocre rating. I had 14 people on my team, and it sucked having to tell someone who was a rock star that they were just average because they didn't do X,Y, or Z. Then I would have to sit through my own performance review, and hear the same spiel from my boss.
Now that I am no longer a manager, I still just don't want to ever have to sit through another performance review. My new manager just put a meeting on my calendar last night to go through my 2020 performance and I could feel my blood pressure rise.