I take shit from people for always needing to sit where I can see the exits and doing a walk around whenever I'm in a new public space. I'm not trained, but I ain't dumb either. Hard to say what I'd do in this type of situation, but I'd like to think I wouldn't freeze up.
I’m the same way as you. I always sit near a exit or know where the closest one is at all time. I also try and put myself in an area where if something does happen I am able to either draw from concealment and put shots on target first, find a place to get under cover and not just concealment and evaluate quickly what to do, or exit the area. After watching videos I realized how people don’t know the true difference between cover and concealment and also that when in a high adrenaline, life threatening situation they loose all ability to function and freeze up. I would like to think that I would be able to think simple and either evacuate the area, or find cover and think of a plan to escape but I also hope I will never be in that situation. I have no prior military experience but I have taken 4 concealed carry classes 5-7 hours a piece offering not only situational awareness, evacuation planning in emergency situation, and how and when to draw and put shots on target effectively, but also on cover vs concealment, how to try and calm your nerves and think critically and rationally in life threatening situations, and also how basic first aid. I know being in the situation is different and a couple classes and simulations aren’t going to prepare me for the real thing, but I feel it has helped me and changed how I think and what I carry on a daily basis. I get crap for going out and not drinking because I choose to carry at all times, I get crap for never wanting my back to a doorway when in public, always carrying a flashlight, a knife, and a small med kit in case of an emergency, but god forbid something did happen, they would be glad that I came prepared for the worst.