All the sensei’s techniques and all the sensei’s skills

mean absolutely nothing if you are unable to train appropriately to the situation, the intent of your discipline being sport, combative or fensive. All the techniques, all the tactics and all the strategies cannot put things to right when they fail, when the intent behind the practice is not appropriate especially when it comes to self-defense because you cannot train the reality of such conflict and violence in a training environment.  

“You can't recreate conflict and violence in a controlled dojo setting because you can't put people in a life-or-death situation” - unknown