In the Israeli army we have a saying. Loosely translated it means "Under pressure, you don't rise to the occasion, you sink to the level of your training".
As a commander I have witnessed this myself time and again in combat. The soldiers who cut corners in training naturally did so when we were under pressure. The soldiers who were diligent in taking proper cover and who took care in executing tactical manoeuvres even when they were exhausted and the officers weren't looking also did so when we were under fire. These small things for a combat soldier in the chaos of battle often separate life from death.
This is the reason why anyone who trains Krav Maga with me whether in Israel, Australia or anywhere in the world doesn't get to cut corners. We practice techniques again and again. And then we keep on practicing them under pressure. Every single time I will insist on accurate and effective striking, aggressive execution and not just going through the motions. Those that have trained with me know how persistent I am with this. I am persistent not because it gives me pleasure to watch you suffer. It's because I have personally witnessed this approach to training save lives.
Train hard, train often.