When I'm making 'good progress' down a country lane, a wild animal jumping out of the hedgerow is the one variable that you just can't account for and is truly part of the lottery of life.
I was once overtaking a car at good speed and a rabbit ran out in front of the car and myself, safely reached the other side of the road, changed it's mind and returned right under both my wheels. I managed to control the resulting tank-slapper but there were a few seconds where I didn't think I'd make it.