No-contact fighters, such as traditional Taekwondo practitioners, think their techniques would be effect in a real self-defense situation. Contact fighters, such as sport Taekwondo practitioners, think that because they get hit on a chest protector or on a foam helmet with foam covered feet and hands that they are more prepared for a self-defense situation than would be a traditional Taekwondo practitioner. Full-contact fighters think that, because they take hits from an opponent whom they respect and with whom they choose to fight, it makes them better prepared for facing a person who is intent on killing them.
Mixed martial artists think their grappling skills will keep stop an attacker, but their training partners are not not taking bites of flesh from their neck or gouging their eyes. All these fighters are better prepared for a self-defense situation than people who have no self-defense training would be prepared, but all these fighters are living in a fantasy world. An attack made in anger with the intent to kill is infinity worse than an attack from the same person in class or under rules of competition. When an evil person is intent on killing you, you have be even more ruthless.
To be effective in self-defense, any technique must be capable of taking out the attacker and you must be able to use it will the intent of taking out the attacker. When it comes to real self-defense, you need to know how to perform properly and powerfully what should be effective techniques, but more important, you must be able to perform the techniques with the intent to take out your attacker.