A better model for a well equipped BOB might be the sort of pack a wilderness SAR member would assemble and keep ready. It would be the sort of item you could pick up, walk out the door, and keep going for about three or four days. Very often you would e departing on a mission at highly inappropriate times - as the gathering storm builds, at high noon on a hot day in the desert, etc. The gear packed within needs to be versatile and comprehensive, rugged, versatile, and yet reasonably light weight.

In most environments, a SAR pack is not something one can assemble and forget. It needs constant adjustment through the seasons. I did SAR in southern Arizona - in summer, the pack was essentially "a giant water bottle," as one of my colleagues phrased it. In the winter, clothing and rain/snow gear received more emphasis (the winter pack was typically a bit lighter). There was plenty of medical gear,proably more than one would carry in a BOB.

There were plenty of times where I picked up the pack, left, and came back about two days later, having used just about everything in it.