ill have a go at this one, i don know anything about krav mega (just very little from this forum, and a few other people)
using your "instinct" i think relates to "natural" reactions...
(i take this from my own martial art..not krav mega...but it could be similar)
for example if you were to go around the street punching people at random, each person would react a slightly different way.
that "natural" reaction is ignored out by some martial arts, most other arts dont incorporate the urge to flinch. or the grab reflex,
i saw a clip of a karate drill were a guy was swinging a stick very close to a persons face...so that person would "learn" not to blink or flinch from and attack so he/she would be better to, i guess counter a punch...anyway you know what i mean
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so most martial arts build new instincts where an art like krav mega mite use more of your "old" instincts.
this is a benefit for quick learning...
i know i havn't been to clear on this idea, my example mite not be to strong but i think iv got the idea across, but i hope i was some help....thanks
Kingston