When you hang an electric hand drill on a nail pounded into a floor joist, you want the chuck jaws to just clear the nail. Too large and the drill tends to fall off. Too small and it won’t go.
I took way too long to figure this out, but…
Adjust the chuck properly just once, then run a fat marker around the jaws.
It’s trivially easy to get it right forever after: spin the chuck adjustment until the marks line up with the chuck nose and hang the drill up.
Maybe everybody else knows that.