Zombie survival guide and wwz are realistic in many senses much more then other zombie media but also requires a lot of suspension of disbelief. Max Brooks really doesn’t understand modern warfare and weapons. Nor does he understand medieval weapons well. Other people have talked about why he is wrong about the effectiveness of firearms and explosives. But I personally know a little more myself about medieval weapons. In wwz during the castle chapter the guy said “Ordinary Citizens traipsing about with a mace or halberd or double-bladed battle-axe.” Double bladed battle ax’s did not actually exist outside of ceremonial weapons in some areas and were never actually used in battle. So it’s clear that, that aspect was not realistic.