In the spring and summer, I usually shave it once every few weeks so it doesn't get too long. But I don't really care if someone has armpit hair or not.
I need someone to post that Taylor Lautner pic fron when he was muscular and he had a soaking wet tight white tshirt on holding a football and his dark armpit hair peaked out the sleeve
It can be a one week long thing but not longer 
Maybe keep it under control though.
unless that person is hairy