On a course i was once given the statistic that at 30mph 90% of pedestrians die, and at 20mph 90% live.

Now consider (from the same course) that breaking isn’t linear and most stopping happens at the end. So if you’re going 30 and would stop at point x during an emergency stop, then if you start an emergency stop at the same point while doing 40 you’ll reach point x doing 30.

Yeah. I don’t speed, especially in areas with pedestrians.