is it just me or is there a secret set of inscrutable rules men follow about when to address someone by their first name vs their last name

some guy will get intro'ed as Joe Schmo in a meeting and all the men start calling him Schmo, and then John Deere comes along and they all call him John. I cannot for the life of me figure out what the pattern is but it happens ALL THE TIME and all the men ARE ALWAYS IN AGREEMENT

Very interested to find out. Once every six months a random guy will address me as Ross. I don't why & never ask.