Most likely depends on the worker that day too. not uncommon at all to see different fasteners used from left & right side on the same car.
lots of variables & the guys on the assembly line had no idea we would be trying to figure out what they did 50+ years later.
I think Those staple guns were like wood framing nailers, easy to put "a few" extra in. just a squeeze of the trigger.
I used to wonder if just maybe some of the unknown grease pencil marks on the firewall and other places were actually meant for a guy down the assembly line & was code for "meet me for beers after this shift"
Now they are in restoration books & countless cars are getting restored with the "code"
Not very likely, but I wouldn't say something like that is impossible
