it's all about your scenario. I would agree that a gieger counter alone is relatively useless. This tool is designed to provide information about how much radiation you are being exposed to, without some other plans / equippment / location / transport / shelter to make that information actionable what you accomplish with a gieger counter is a precise understanding of exactly how f%^*ed you are. This doesn't really increase your chances of survival. OTOH if you actually have a place to go that is secured from radiation and a way to get there that is likely to be usable during a disaster (bomb shelter and helicopter) then you might be able to use the gieger counter to let you know when to get into the helicopter.