I was a teacher at a small rural school. Five people in my department. Our department head was the worst possible choice for the position - she wasn't the most senior, wasn't the best equipped, wasn't the most innovative, wasn't the best peacemaker. She bullied and belittled, her lessons were the same for years, her scores weren't even particularly strong. We frequently went to professional development as a team which she didn't attend. Couple this with an admin who was incompetent and constantly double talking and it was a giant pain.

The final straw was when one of our colleagues found a better job (department head at a neighboring school) and they needed to reshuffle classes to find a replacement. Despite being more qualified and more experienced, they refused to give any honors or AP courses to me or my colleagues, instead hiring a first year teacher with only a BA and shutting the rest of the department out of the entire hiring project. We were literally in the building running summer school and planning for the following year while they did every interview with no input, promised to talk to us, then made their offers and class decisions. We were told that we'd all meet to discuss it, then they reversed course and said they didn't want input and we'd instead have a meeting at the start of the following school year to essentially admonish us for not blindly following our department head.

We finally decided we'd dealt with it enough. Three of the five of us left that summer, the fourth left the next year. They had to hire an entirely new department because of that one person. I'm in a better school with a better team now, one of my colleagues was poached by the same one who was originally leaving, and another sold her house and is touring the country in her RV home. The superintendent fired the admin the following year as well.