We live on a small airport with neighbors who own and fly aerobatic aircraft in formation. I have never had any desire to do that type of flying and am very happy with our Piper Cherokee which is extremely easy to fly.
But before I started flying General Aviation aircraft, I flew ultralight aircraft and hang gliders. A lot of the places where I flew hang gliders when there was not much wind, there would be a dozen of us sharing the same ridge lift. I had one acquaintance who was much older than most of the rest of us and he was a menace. He had several midair collisions where he clipped other people’s wings and somehow was never injured or caused a serious injury.
Fortunately, we were all flying the same direction at low speeds and far enough above the ground that everyone was able to recover after being bumped by this guy. The only injuries were caused by extremely harsh words shouted in strung together in profane outbursts.
Are there common courtesies for hang gliding? Take turns taking off? Minimum distance between gliders?
In WWII, “formation flying” was a required study for US Navy pilots.