I want the switch that allows me to turn this on at will.
If I understand this correctly, the immediate fight-or-flight response is triggered by noradrenaline, which is very similar to adrenaline but released by nerve cells directly to places all over the body, increasing blood flow and pressure, alertness, etc (but not affecting muscles). Adrenaline gets released into the blood via stimulation by the sympathetic system, but its effects last longer.
So it seems noradrenaline, by the fact that it's released directly from nerve cells, basically dictates how fast a person processes immediate external stimuli, and could possibly explain "super perception"
As with so many other things in the brain, there's a reason (metaphorically speaking) why it works the way it does. Anything that's a small tweak away, like more perfect recall (which evidence like the woman in the article suggests can't be that distant from how our brain works), but has not spread through the population, probably isn't that useful. (With the caveat that our environment has been rapidly changing and what's useful and not may change. Though the woman in that article doesn't seem to be a beneficiary of the effect.)
The standard (and best) answer. From experience there is another factor to take into account, randomness. Each situation is unique making how you adapt important. It's never quite like the drills. Training allows you to adjust quickly. With training the skills are there ready to be applied and adapted to the situation at hand.