Rumor from my Irish barber: the difference between the spelling of whisky or whiskey correlates almost perfectly with whether the country of origin has an “e” in its name. (For purposes of this game, Scotland is considered a country.)
I’m not convinced and want to hear from the Farm! Yes, Japan spells it without an “e”. The sole major outlier in the USA we found was Maker’s Mark Whisky, trying for a more effete look.