I look at this in terms of layers. I wouldn't want to ever have to rely on the tools in my PSK. They are small, minimal and few. That being said they provide an edge in the environment for which I carry them.

These are the scenarios that I prepare for and the kits that fit.

If it isn't in my pocket I'm toast

Surprises in the course of a day. This includes everything from power outage at work to terrorist attack that puts the entire city into a panic. For this scenario if my EDC doesn't coveer it I'm toast. This is the PSK and, if I'm lucky enough to be able to get to it, my car pack. I have considered having a desk pack at work but I work in a single story building with my car in a parking lot where I can see it from my desk so I haven't felt the need. OTOH, if I worked in downtown hi-rise ...

If I can't carry it on my back for 20 miles I don't have it

Events with 1 hour to 3 day's preparation time requiring evac. These are the BOB scenarios. I consider my BOB a house on my back type of scenario. If I am evacuating it is very similar to going on a long hike (think thru-hiking). If I can evacuate with my vehicle it is more similar to car camping. In any case the only thing I take along when evacuating that I don't when camping are my documents. (title to the car's and house, mortgage and loan papers, lisences and credentials, Zip disk with the last 7 years of taxes and other sundry documents, passport, birth certificate, insurance documents, medical histories)
My normal camping gear has a triband handy-talkie, my car has a triband mobile rig, my hip has a cell-phone. I don't bother much with the commercial radio but I do have a small credit-card sized am/fm with earphones that I got at the dollar store.

If I can afford it and know how to use it I have it

Events which require digging in and sheltering in place. This includes earthquake / storm / and some social unrest situations.
This kit doesn't have to be carried and is stored mostly in the shed out by the driveway since even if it is knocked down by the storm / earthquake it isn't so large a structure that I couldn't lift sections out of the way and get at my kit with my bare hands and the leverage of a stout piece of lumber. This kit includes some large tarps to cover holes in the house, some shoring up lumber - nothing short of a 4"X4" lumber would be safe. 2"X4" works well in structures when used in numbers but will snap if you use it to shore up things temporarily. (If you have skill and experience in construction then disregard that last) Pry-bars, leather work gloves, zip-ties (the larger the better) hammer, nails (the larger the better), rope, wire, honey bucket, wag bags, tp, bio-blue for the honey bucket, shovel, canned food, water, soap, tent, screen tent, water pails (5gallon buckets), barbeque with better than 1/2 full propane tank - large - this comes in handy even when there isn't an emergency <img src="images/graemlins/wink.gif" alt="" /> and of-course weapons and ammo. These last are locked and hidden from casual disturbance out there in the shed. But I may not be able to get into my house easily after the quake knoks it off the foundation - tornado blows the roof off - blizzard squishes it with snow weight etc... There's a bunch of other stuff out there too that would be considered normal shed stuff like the chain-saw, lawn mower, etc... which will come in handy in an emergency. There is probably the ingredients of some reasonably powerful munitions there as well between the kerosene and fertilizer the moth balls, paint-thinner, oil, soaps, etc... A little research in the library of survival books tucked into the corner will yeild a treasure trove of interesting entertainment from that shed. <img src="images/graemlins/smile.gif" alt="" />