Me neither Alan. I think it's the kind of 'advice' people repeat without thinking about it, or considering shorter boats
My centreline is approx the same length as the boat (very useful for singlehanding!) but in 7 years it's never been anywhere near the turning prop - because I'm aware of the danger and, as you say, I'm disciplined about always coiling it up and putting it on the slidehatch when not in use. Which also means it's ready for the next time i need it
I don't leave the boat in gear if I'm not on it either
I always strap if possible - why use reverse and swirl up the water if you dont need to