The main reason for my PSk is my tendency to borrow gear and never replace it. So my PSK is mainly a double of what i carry. I always refrain from taking stuff from it so if I need something i wont realise that I just used it last weekend and didnt have time to put it back.
This is pretty much the reason I carry a separate PSK from my normal bushcraft items, and I don't touch the PSK unless I'm in a survival mode (which I have fortunately not had to use other than to practice).
I also don't mind redundancy of key items anyway. I usually have 2 firesteels, one on me and one in my PSK, in addition to 2-3 pieces of fatwood spread about, lots of cord (I like cord), couple of compasses and so on. I have been acused of being an adult "Boy Scout" and honestly try to live by their motto - BE PREPARED!
Charlie