Imo instaproning is way more detrimental. As regards the jack in the box technique and the ability to 'fix' on a target before popping up and firing, this is in some way realistic. In RL you would not stick your head up and then look for targets. You may just pop up and put rounds where you think the enemy is most likely to be, but generally this is done in conjuction with other squad mates as part of a concerted and organised effort to suppress the enemy.

Otherwise you would perhaps sneak a quick peek and look for giveaways like muzzle flash and then only pop up and take a shot if you had one, i.e. a good fix on your target. Before doing so you would have a mental picture of the shot and would visualise your actions. This creates a kind of short term muscle memory if run through a couple of times that reduces the thought processes to automatic steps thereby speeding them up and limiting your exposure. You would also move, hopefully unseen, to a new location before each attempted shot. Movement penalties make this a slow process in PR so people stay put and basically play russian roulette. To be honest neither party in these shootouts is playing very tactically or realisticaly. The 'jack in the box' should be comms with his squad mates, talking them in on target and simultaneously requesting suppressive support to enable him to safely exfil. His squadmates can then suppress and flank to eliminate the threat if desired. The aggressor should be doing the same and to some degree be more interested in suppressing and pinning the 'jack in the box' . Unfortunately due to player mentality both are generally more interested in the short terrm kill and intead of valuing their lives and tickets and realising that there is an opportunity to possibly wipe out the whole squad if the situation is developed correctly.

As a result of wanting the kill rather than the suppression the aggressor subconsciously pauses a split second when firing, waiting for the 'jack in the box' to pop up, because they want the kill and are going for confimed hits rather than simply keeping their opponents head down. In addition they will probably be working alone instead of suppressing with a squad mate. Suppression is exponentially more effective with more people involved. Extra shooters mean continuous suppression, cover for reloads, cover for shifts of position, multiple angles of fire etc. When it's one on one you're effectively playing out a 50/50 duel, instead of stacking the odds in your favour by being tactical and playing smart.

I think that these situations, if looked at in a different way, are realistic because they should eventually force the player to adapt more realistic tactics if they want to be successful. Forget the reasons or mechanics, look at the outcome, the game is actually telling you not to get involved in lone, roll of the dice shootouts, its saying 'use your squad, suppress, move, flank, eliminate'.