The training department has never taught to check the status of the headset. If someone did it was only technique as it’s not in the fcom. If you follow the fcom verbatim the first instance on a typical day an FO would notice a headset unplugged would be either calling for route clearance or push.

The parking brake preference is aimed more at heavies as they heat up more and cool much better with the parking brake off. Also zero chance to get the brakes to lock up on you with them off. I’ve seen it and it’s not a fun time for MX.