I think it is a great idea to look at the assumptions that go into assembling an bug-out bag, and the implications of those assumptions. Here are some suggestions:

Assumption: You do not know when you may have to grab your BOB and go.

BOB Implications: You will not have time to pick and choose BOB contents - it pretty much has to be ready to go as-is. If you live where there are major seasonal environmental variations that necessitate different BOB contents, then you better repack each season (or have a BOB for each season).

Assumption: Your BOB contents will be guided by the Rule of Threes (You may die if you go: 3 minutes without air, 3 hours without shelter, 3 days without water, 3 weeks without food).

BOB Implications: You want gear that lets you breath: particulate mask, your medically necessary inhalers and antiphylatctic (sp?) shock gear, and whatever first aid gear is reasonably carried to keep you from bleeding out from injury. You want clothing, including footwear and headcoverings, and gear that can provide shelter from the elements if you cannot find shelter. You want to carry water and food, and the means to find, treat, and carry more if your supplies are not sufficient to reach your projected next source of re-supply. You want to carry more water than food.

Assumption: You will have gear in each survival category, including First Aid, Shelter, Fire, Water, Food, Navigation, Light, Signaling, Self-protection, Hygiene, and Morale.

BOB Implications: With so many categories of gear, you must severely limit the stuff in each category to the most necessary, with a priority on stuff that is compact, multi-use, durable, maintenance-free, etc.

Assumption: You need to travel, on foot if necesary, to reach your next source of re-supply.

BOB Implications: You want excellent footwear and foot treatment supplies. You want light-weight gear. To cover distance you want food and water sufficient to spend minimum time foraging. The overall weight and size of your BOB must match your physical ability to walk for what may be an extended time. You have whatever you may need to navigate to your next source of re-supply in what may be a highly altered environment that no longer allows shortest-distance travel.

Hypothesis: While we may have preferences and economic limits that show up as variations in specific gear, the contents of most BOBs will be remarkably similar.