Speaking of that, what if it's not a person at all, but a big dog,or a pack of dogs, or a rabid dog, or raccoon, etc?
Or circus ponies. Mustn't forget the circus ponies. Your martial art is worthless if it doesn't train you to deal with the sudden, completely out-of-the-blue appearance of a herd of enraged circus ponies, all determined to trample you to death. How can you say your martial art trains for self-defense if it doesn't teach you that? Sheesh.