Typically, most people prefer to 'write-off' their BOB's. Meaning, you assemble it and then you leave it alone until you need it (other than to check gear, update gear, or replace expired items). The idea being, everything will be there, in good working order, when you really need it. Trying to find items you took out for one reason or another can cost precious time; which is completely opposite of what a BOB tries to achieve (everything in one place so you can just grab it and go).

With that said, it's a difficult thing for a lot of people to do, as gear isn't cheap and you don't/won't know what gear works until you try it.

My first BOB basically started as a dumping group for older gear. As I bought something new to replace an item, the old items would find their way into one box as long as they were still in good working order. In a couple years I had the beginnings of a good little BOBox....and because they were older items, I didn't mind writing them off.

Finally, it's worth keeping in mind that the gear list for a BOB isn't exctly the same as a gear list for camping. I mean, I don't usually take copies of my important papers, dust masks, and pry-bars camping...but after 9/11 I consider them basically essential to my BOB.