There are occasionally "air holes" happening near my local airport. A friend onboard a particularly severe one told me that the captain said that they'd "fallen" some 160 meters. I also have another friend who, a long time ago, didn't use the seatbelt on a domestic flight - sudden turbulence made him hit his head and injure his neck badly. That's very dangerous. Personally the "worst" I've seen was just enough to break wine bottles in the overhead in front of me. Flight attendants gave out blankets for all of us nearby, as protection for dripping wine..

Trans Tasman too now.

According to the below, long haul flights get it more, due to the altitude they fly at.

https://en.m.wikipedia.org/wiki/Clear-air_turbulence