Not necessarily but it’s a matter of muscle memory. Civilians also do not duck at times and can freeze over - depending upon the individual or response.
I remember back in 1999 with Kargil I was barely a kid and we used to have some military folks come to our place for late tea and they were showing recordings of Indian troops being hit by shells and bullets on the main trunk that was being targeted and they stood there like mannequins and getting ripped apart like rag dolls after a shell hit again and again - not just because of training but it was the suddenness of not expecting to be hit there.
In another video online of Pakistani forces clearing a compound it was plain training - no concept of corners or covering each others blind spots they take needless casualties but it was “Pakistan Zindabad” at the end. I showed it to a US soldier who was so dismissive of their tactics stating “these guys consider their men pretty expendable”
Its a matter of training not just from initial training but constant drills. That happens for Pakistan’s SSG but the regulars(on average) are generally equivalent or lesser trained than reserves of most western armies.