ALways shut down. No matter what.
Did someone eventually come along and turn the key off? Gas is expensive.
You walk out to the end of the wing before turning one way or other, or, walk directly to the back of the plane to leave the area while the prop is still spinning.
Henry duPont III died that way. Somebody left the engine running, then inadvertently hit the controls as duPont was unloading luggage. Some reports had it he was struck by a propeller but as I heard it from a more reliable source, the plane started moving and duPont fell off.
Way before my time, maybe 1970’s?