Okay, here's my thinking on the 72 hour kit, and the situations you need to use it for.

the 72 hour kit is intended to get you through the actual event, and either get you through till help arrives if that's possible, or give you the chance to get out and find better conditions elsewhere, or retreive essentials to extend your stay. The 72 hour kit is big enough to get your through the critical period of the event, but small enough to be portable. The 72 hour kit is not the same as a shelter in place kit, which would be more robust to provide for an extended stay without the means for egress or re-supply.

Here's Doug's take on the 72 hour kit:

http://www.equipped.org/72hourkit.htm

Doug's blog on 8/30/08 is worth the read too. It speaks to the mindset of our Society, and this "help me" mentality.

His contention is premised more towards the staying put needs, vs the notion of moving out once the weather settles down as I prefer. I guess it depends on what you perceive the 72 hour kit's purpose for. For me, it has never been anything more than to get me by during the storm, or the eruption, or the whatever, until I can emerge and seek life elsewhere. The last thing I intend to do in any temporary crisis is sit around and wait for help to come to me (yes, there are exceptions, again, not what I would plan a 72 hour kit for). If I am immobilized, then I have needs that would exceed even a one week kit I am sure, knowing what it would take to immobilize me like that.