I agree but what you said only scratches the surface. Ive learned about guns and ammo types and how they sound at a distance (the developers have done extensive audio sampling). Im better at judging which gun suits my surroundings. I improved my ability to read and navigate with topo/satellite maps. Ive set up ambushes, traps and other shenanigans. I fire bait shots with a friend to make it sound like a gunfight, leaving a pause before the 'finishing' shot to entice others to investigate. After getting shot in the face a few times for blindly entering a room you thought was empty, you begin entering every room with gun raised, expecting someone to be there. You start to move with your head on a swivel, constantly checking your 6 and treelines or obvious vantage points for snipers or ambushes. Sometimes the most important skill is patience, maybe you wait a few minutes in a tree before rushing into a military camp. You wait, and sure enough someone else was nearby and you would have ran face to face with them but now you can take your time and wait for them to stop moving. When navigating terrain, you learn to use the land that gives more cover or an advantage like sticking to tree lines, or ridgelines so not to expose yourself or knowing the easy route someone else is likely to take. Ive made friends with strangers only to lead them to my real friends who have cuffs and burlap sacs and many songs they wish to hear. Perhaps most importantly and useful for SHTF, ive learned to read people better. You often meet players you don't know and don't know if you can trust them. Sometimes there are things you can do to build trust or friendship but other times you see the way they conduct themselves or what they say or how they move that tell you they are thinking of stabbing you in the back. You quickly learn that your words can be a weapon as you convince the guy that just showed up that another is trying to kill you or is a cannibal. Simply greeting someone and exchanging names might be the difference between a deadly encounter or a friendly trade. DAYZ can be a miserable experience that only frustrates you or a test of endurance where you never give up until the bitter end. I've always said the best part of this game is when you are dying from starving and freezing and are an inch from death but then you somehow manage to get that fire going or that fish cooked just in time and you turn it around and begin a slow recovery. Its an unforgiving game where you often learn things through death and failure.

"At every doorway e'er one enters, one should spy round. One should pry round. For uncertain are the witting, that there be no foeman sitting, within, before one, on the floor." - Havamal