IMHO the BOB, Bug-Out-Bag, was intended originally to just get you to a remote site or safe area. Presumably this is just a few days away and there is no need to bring supplies or materials because everything you need is already there.

It is to be assumed that the distance to the remote site is close enough, and/or transportation arranged in such a manner, that the trip will be relatively quick. Traveling in an emergency is always problematic. The amounts and types off supplies and the ability to set up and get rest are limited and problems multiply. The point is to get there in a timely manner not to undertake a pilgrimage.

With this in mind a lot depends on how you travel and what conditions your expecting. Traveling by truck allows you to carry more than humping everything in a pack. IMHO most people who are looking to live out of a pack would benefit from looking into hand-trucks, carts and bicycles.

Also, the sorts and proportions of what you pack is going to change if you are planning to be fleeing a hurricane, plan on two weeks of rain, or shooting your way out through waves of zombies. Rain and zombies would suck. Toss in fallout and an ever-present superbug and your into vast new horizons of suckage. Fortunately fiction often sucks more than reality and limiting yourself realistic scenarios simplifies things.

My strategy is to cover the known and expected. Worse case, graboids with AIDS and super volcanoes, I figure I'll have a leg up on that also.