I have after a long flight put some on the outside of my clothes or underwear in the crotch area. They don’t happen to have showers or very convenient bathrooms on airplanes (unless it’s a super duper private airplane)
Sure there may be times when it would be a good idea, but I meant that I was joking about it being common and polite as if everyone does it and expects others to do it too
The antiperspirant part may not do much about the current odor, but it does keep it from getting worse. I’ve known people to put on antiperspirant before doing some strenuous activity for this very reason.