Whirl you know why they train center of mass because many officers can barely qualify to have their gun, i see it on the range i go to, at 20 feet some are lucky to get all of them on the paper have seen several of them have to redo several times to get a pass usually with pressure of chief firearms officer from their boss because of man power.
Add to this most places a cheap with ammo and some frankly never go to range until time to re qualify and you see why aim for the com is what they teach, even though you are completely right about the need for ability to hit what you aim at.
that is why you use a patrol set up with scouts flankers and rear guard and everyone knowing where to go when it goes wrong. this takes time and practice on rough terrain and in confined ones so everyone goes same speed. You will need coms and such but most folks dont have time or dont think it is important enough to train doing this with full gear. let alone with working on diminished personnel or having “injured”.
For after shft will depend on technological sophistication of you vs your opposition, you have night gear they dont well move at night ect moving at night quietly is a skill that is difficult to learn over many environments with a group and not leaving a trail. there is a reason why recon is small 6 and under in size for most non base deployments. As for snipers well how good a shot are you , if you can spot them, a person who passes a stalk to get the pass will basically be invisible to 99% of people till too late. Stalk training here is over 12 months everyday after passing the shooting qualifications, then you can do additional mountain training. the will hit at about 800-1200 yard is a dead sure kill box with even a hunting rifle. dependent on equipment and guys 2400yards is still in range.
you will never see them at 800 at 2400 not a hope in hell. In Selco area they where shooting through building holes to kill people, as a normal people you have very little chance against such a team. just run and hope they choose someone else as a target.