Speaking to hiking/backpacking specifically:

My pocket kit (Altoids tin) is always on me. In my pack I carry total redundancy for everything in my Altoids kit. And more. And bigger. e.g., the BSA HotSpark in my Altoids is redundantly backed up with a Swedish army firesteel in my pack. (Other firestarting stuff in both the Altoids and pack as well.) The polished reflective lid of the Altoids is backed up by a redundant StarFlash mirror in my pack. Scalpel blades in the Altoids have a Cold Steel SRK backup in the pack (and also a folder in my pocket). 10' of paracord wrapped around the Altoids is backed up by - who knows how much? - but a bunch of paracord in the pack. You get the idea. My thoughts being, I hope to have my pack and all the bigger, better, and more stuff, but the pocket Altoids is always on me.