I have heard that you lose coordination when you get that adrenaline dump when you are angry, shocked, stressed, or scared. Or is Xingyi applied freestyle like wing chun's chi sau?

Someguy

At least as I try to practice them, movements flow with ones natural reflexes, rather than something contrived, such as karate. This way instinct and training enhance each other and the loss of fine movement and dexterity under stress is not a problem.

Blocking in Karate or any art is mostly reflexive... & most all else in karate is striking & manipulating which are learned responses...

This conceptual mix-up occurs because many Okinawans & Japanese say "block" when teaching English-speakers some of their strikes & parries (esp. various forearm strikes)... just something either lost or crossed-up in translation.

Blocking is natural & reflexive... everyone does it everywhere, regardless of style (without style)... Okinawans wrestle a lot -- it's what they've always done (as a country-wide sport... like kids will do in a sandlot... fun & competition happen... & what else are you going to do on a small island?)... the addition of karate practice only helped to round out their martial experience.

Admittedly, the way some instructors of karate teach, their methods become quite contrived... but I wouldn't say that good karate is any more contrived than good Xing-Yi or good Tai-Chi or good western Boxing or good Shen-Wu (note: there are few good practitioners in any combative art).

Also, admittedly, there can often be a fine line between a contrived strike which blocks & a reflexive blocking reaction: the fine line being thoughtful-action/reaction vs essentially thoughtless reaction... once a contrived/planned action is drilled well, then it will require little thought & be almost as fast as a reflexive action which requires no great/perceptible thought.