Not really, as stated by this post
Headless Horseman Mount - Support / Customer Support - World of Warcraft Forums (blizzard.com)
If averaged out over several thousands and thousands of attempts, yes it’s possible, otherwise it’s literally a 1% drop rate every time. And the % you see listed is based off those thousands of attempts by hundreds of thousands of people, so it doesn’t really apply to one persons luck at it. However, people like to argue it because of how statistics work elsewhere.