So now you can defend your self pretty well from the undead. How will you defend yourself from the living? People will be hungry, tired, and in a desperate state of food, water, and shelter. What will you do to defend yourself, your supplies, and your shelter from those willing to take it away for the means of survival? Will you build traps? Will you have a well secluded and well walled up place to stay? What about vehicles and heavily armed people? How will you survive against the living?
Zealous evangelical religious groups bent on hunting any and ALL that oppose the word of god(s) gangs of raiding and pillaging people always on the move killing anything in their way a "king of the ghouls" separatist states formed by strong gangs cannibals good people bent on helping others in a civilized and peaceful way Rogue military/civilian units claiming land and other stuff as theirs Etc etc etc.
I base my predictions in the U.S by U.S citizens usually thinking about the midwest and pretty much every major city and country side. You got the good, the bad, and the zombies.
isn't world war z a good example of a volley fire? When Todd (the soldier guy from Yonkers) talks about how they went to New Mexico and set up a base and had rows of two that held off hundreds if not thousands. Their training was firing on the range with a metronome. A monotonous and rhythmic firing in single fire.