One of the most important concepts that I have learned from KMG is the timeline of attacks. What we mean by timeline is that attacks develop over a period of time, one that is unique to each attack. The point in time where the attacker has decided to move against you, and that sequence of events meets you in reality, determines your response. A response from you early in the timeline will likely not work at the end of the timeline.
Learning to recognize attacks
Why is it that we need to train for so many years if we could simply avoid be attacked in the first place? The answer is that we can only respond early if we recognize the attack, and one of the best ways to recognize the attack is to have seen it many times previously, making it very recognizable.
I like to say that we would rather you prevent being choked than escape from a choke. However, the only way to prevent being choked is for your brain to recognize that a choke is imminent, and have the associated motor skills to respond in a beneficial way.
Mastery in self-defense / fighting is having your brain recognize the attack that is developing, and to begin the correct response to that attack immediately. Imagine we take a video of an attack and look at the individual frames of the video. If a few seconds of film flash by at 30 frames per second, a novice will only recognize the attack near the end of the video, after hundreds of frames have passed. Their ability to respond and the type of usable responses will be limited by that point in time.
If you were to compare that to a master, ideally they would have already recognized and simultaneously started to respond on the first frame. Your instructors / masters are not necessarily physically faster than you are. They have simply seen the attacks so many times, and performed the correct responses so many times, that they react immediately.
Freeing your brain
If your brain is able to respond pretty much on auto-pilot to a stimulus, it allows you to start thinking at a higher level. Instead of worrying about what hand they are striking with and how to defend it, you are thinking about 1 - 2 moves ahead, learning how your opponent responds to certain stimulus, and able to deal with higher level problems.
This is why we spend so much time focusing on the fundamentals of movement and striking. It takes literally thousands of repetitions to achieve mastery of any particular movement. Sometimes this seems boring, but the end result is that your mind is capable of doing the necessary in the moment while starting to think ahead to the next move.
Applications beyond fighting
The timeline of an attack may extend many minutes, hours, days or longer prior to any physical contact. This could involve all kinds of stalking or other pre-attack indicators that are situationally dependent. Once we intimately know the behavior of attackers, we can learn to see indicators much earlier than most. We like to say that are "prepared, not paranoid", and this is what we mean. You become much more situationally aware of your surroundings.
One of the benefits is that other types of problems, such as dealing with potential accidents, become easier to predict and respond to. You see the warning signs of road rage much earlier and begin processing your response sooner. When someone is about to fall or cause an accident, you can see it and respond earlier. (A simple example - I once saw a waiter next to me with two plates of food on it. I knew if she removed the wrong one it would be off balance and cause the other to fall. As I thought, she grabbed the plate closest to her, causing the platter to become unbalanced and tip over. I grabbed the now-in-flight plate from the air and placed it on the table. It looked like I was fast, but really I just anticipated the accident.)
The answer to all things is self-defense is "keep training." At some point in your training career you will start to understand that the techniques you have been working on, are now working on you. Training systems have been around for thousands of years for a reason - they work. A good training system will cross over into vast parts of your life, not just your physical safety while under attack. The key is to keep training - forever. As in most things, those that persevere achieve the greatest rewards.