It might, particularly in sparsely covered areas. In a more densely covered region, there would be so many towers to make note of, it might be easier to just walk around a bit in search of a signal. If you live in a densely covered area, that also means that it's a densely populated area, and the cell towers will likely be overloaded with callers during some crisis situation anyway, so it might not help too much in the end to know where towers are located. So many people will be wandering around looking for a signal that all the nearby operational towers will likely be overwhelmed anyway.

An alternative might be to think of tall buildings or hilltops that you might use to try and hit more distant cell towers in case the ones in your vicinity are inoperable. You may be able to reach a more distant tower without actually having to move very far from your location, if you can just get up higher.

Having two phones using two networks would provide you some redundancy, although at added expense. You often hear comments from people after disasters, like major hurricanes, that carrier X was totally down while carrier Y was always on, so the idea has merit. In Europe, I guess you could accomplish the same thing by simply swapping the SIM cards between carriers. I hear a lot of people who travel between countries there routinely pop in different SIM cards depending on where they are, to get the lowest rates, so it's not a new idea for them, and you wouldn't have to worry about keeping two separte phones charged up all the time, in preparation of some disaster.