I would think that would be a good idea depending on the reason and where you live. In a hurricane or flood prone area, one type of bag. In an area where there's the possibility of a riot, another type of bag. It's interesting to think about what you would put into such a bag, such as extra $, power bars, water, a gun and ammo, matches, flashlight, batteries, etc, etc.
i suggest you have several flash drives in your b.o.b. with all your important documents and pictures saved on them.