The other day, my son was showing me his "Threat Analysis." Yesterday, I did a search for a list of disasters in the Pittsburgh area. Other than very local disasters (house on fire, chemical spill down the road, neighbors meth lab, etc.) there were only a few that I could find. The Great Fire of Pittsburgh in 1845 (
https://en.wikipedia.org/wiki/Great_Fire_of_Pittsburgh,) the Johnstown Flood of 1889 (
https://en.wikipedia.org/wiki/Johnstown_Flood,) the crash of USAir Flight 427 (
https://en.wikipedia.org/wiki/USAir_Flight_427,) the crash of United Airlines Flight 93 on 9/11 (
https://en.wikipedia.org/wiki/United_Airlines_Flight_93,) and two blizzards for which I have been present. Beyond this, there are occasional utility outages, but they normally only last a few days to a week.
Of all of these disasters, the fire, flood and plane crashes caused a tiny number of people to need to bug out. These bug out situations (plus the very local disasters mentioned above) were for a very limited length of time (a couple of days,) and could be spent at a friend's, or relative's place, or a hotel. (Although, the fire was rude and trashed everyone's belongings,

but that was nearly 200 years ago.)
The blizzards were bug-in situations. In our 30 years here, we have had only a few blizzards, and they were all over within a few days (the 1993 blizzard - one of the worst - actually had all of the snow melted within three days.) A weeks worth of panty has been plenty for these blizzards.
Pittsburgh is really a pretty polite (disaster-wise) city. To handle all of the historical bug-out disasters, all you need is a 72-hour kit in your car, with money for a few days at a motel. For the bug-in disasters, a weeks worth of food and a well-stocked blackout kit is all you really need.
This, of course, does not cover all possible disasters (solar/nuke EMP, attack on our nuclear power plant, pandemic, etc.) So, I am continuing to build up my bug-in pantry, and blackout kit, supplies. I also have a reasonable 72-hour BOB for Mrs. ChEng and one for myself already in the car (along with a few MREs, my field jacket and several blankets,) and enough money for four nights in a motel.