I learned to drive a "standard" transmission (That's what my grandfather called it.) in a 1969 Dodge pickup with "three on the tree". I don't think it even had an e-brake, so I parked it in gear. No particular gear - just the one I was in when I stopped. Later I delivered tires for a summer job in a Chevy 454 dualie. I always parked that truck with the e-brake and in gear because it had a bad habit of popping out of gear.
I've always used both since then. It's just a habit. I have no idea if you can knock a modern MT out of gear just by opening the frakkin' door.
