Again this depends on the ability of the individual karate student. The most adept technicians in the world, who train constantly and have devoted their lives to mastering the art, are certainly able to vanquish multiple, variously armed attackers under most circumstances. The key to this is highly developed timing, reflexes, and accuracy as well as developing sufficient power to disable an attacker with a single blow. The average karate student with only limited training experience may not be able to do the all the things you see on TV, but his karate knowledge could nonetheless save his life.