In addition blowing air and holding your breath was believed to protect your solar plexus. Perhaps all it did was helped tightening your abdominal muscles...
Another Approach is to keep moving and evade the strike and another was finally to preemptively defend the strikes.
Guess the consideration was what you can do as a function of your awareness. This is what is called the reaction time. While it is a good idea never to waste your time, preemptive striking is always good especially in a sports match.
However, if caught by surprise you might need to learn to last second block a strike, or evade it, or perhaps even take it with least amount of damage.
You must consider that a proficient opponent needs a split second of distraction to find a way and control you by either inflicting nerve pain on one of your pressure points or causing yours body systems to start to shut down out of emergency state sensing a knife cut for example. You cannot afford wasting too much time of the last resort of protecting yourself from maximum damage, since any impact causes distraction giving your opponent enough time to finish the job.
It would be good and obvious to evade a car trying to run you without executing a counter attack.
Immi’s idea was to go with the natural Instinct of Humans and built on them when it comes to last split second solution but to stretch the concept of awareness to all stages of training as well.
So was the time constraints and limitations of reaction explored to basically call the time to the Self Defense trainees of what is the next move they will be still able to execute to save their lives as it was getting closer to the end.
It appears that you have two common approaches: one is that it is good to practice a lot of defenses to the “common attacks,” taking into account that you really do not want to teach how to kill or inflict severe damage back since you are living in a civilized society.
The other is that you need to make your life easy and stretch the definition of self defense to its maximum so you will have a pretty good realistic idea what dangers you are about to overcome and then teach the worse case scenarios to give your students the most challenging drills and the way to overcome them.
Of course the time constraint and the ability and perception of Instructors and Students set the tone to the Instruction, but the worst case scenario is that the complexity of this Hand to Hand Combat Training system opens up a can of worms to the average folk and instructor where there are no rules on any level of the matrix including the intelligence, honesty in business or perhaps you should call it the sales pitch and bait and switch.