I decided to quit for the night, I don't stop welding and head out. I check and make sure everything is cooled down. Not really an issue with our old cars but doing collision on late model stuff that's got all that foam and what not in it will sit and smolder and go up in flames. I'm paranoid I guess.
Yep, From years of 'hot work permit' procedures been drilled in... I never leave the area for at least half hour. Then follow with at least one more check later.