I came off just the once, someone had fitted a tilt and turn window upside down.
As I reached over to detail the top right hand corner, I was holding onto the top of the frame by my finger tips just to keep my balance.
The window had been left off the catch and opened out from the top pushing me off.
One broken metatarsal. I ended up on the lawn, managed to get up and hop over to one of those rustic garden seats made from logs, I plonked myself down on it to clear my head, and the bloody thing snapped in half like a carrot. Just wasn't my day, but hey, the ladder never moved.
I have always used stabilizers with my own design feet, never had a ladder slip yet.