I carry a tailored pocket kit with me wherever I go, simply due to how easy it is to throw into a pocket or backpack. May as well carry one if you have the space, right?
Note that I said tailored. It's not a commercial tin and it's been constructed to meet conditions in South-East Queensland. As such, it carries items I know will be practical in this region.
I've had cause to use my folding knife, ferro rod and tube of super-glue for all kinds of purposes, but only once in something close to a life-or-death situation. I'd torn a deep gash in my calf after getting caught on a barbed wire fence. Since my kit contains a dozen water purification tablets, which double as prophylactics when dissolved into a cup of water, I was able to get a fire going, boil the billy (context: this was during a fencing repair run on the farm, so I had the ute and what amounts to a full camping kit at hand) and was able to mix up an antiseptic solution. After cleaning the wound to the best of my ability, I glued the gash back together. Didn't have time for stitches, so super-glue it was. It held up long enough to get into town and drop by the clinic, and I avoided infection, so the puri-tabs must have done some good.
Moral of the story: Carry a kit with you, but only carry what is practical for your expected conditions. For me that means not wasting space with fishing tackle and cold-weather gear. Still keep a space blanket in there with all the necessities for a rough and ready shelter, but everything i did to patch myself up could have been just as easily achieved with local bush ingredients (melaleuca leaves, acacia sap and palm leaves for bandaging).
It's always worthwhile to carry a basic kit tailored to your environment, but commercial tins try to be all-in-one and thus are practically useless without adequate practice and foreknowledge of the conditions.