The techniques I mentioned, don't need years to train. They are basically the 'quick fixes' of martial arts, designed for those who cannot take to the rigours of more mainstream arts like Karate, Wushu, TKD, Silat, Muay Thai, Kalaripayattu, Thang Ta etc which need years of training and are deadly.
These techniques were developed simply to subdue to opponent enough to make them think 10 times before attacking you.
Aikido, Jujitsu etc were developed to use the enemy's aggression against his own body.
Krav Maga was developed as a result of learning to fight fast, relying on your body type's basic instincts and in a short time by Israeli soldiers.
Even lean-framed women are capable of learning these and can take on much bigger guys trying to attack them.