I've been carrying a highway flare in my saddle bags, and in my day pack, for about 35 years. Of course I also carry the other standard fire starting items, but I've been in two situations, one in s.w. Colorado, and another in the high Sierra of Calif., where I HAD to use them in an emergency.
In Colorado, my partner and I had got an elk down just at dusk. Unfortuantely, it had been off and on raining/snowing for several hours. It was miserable, but that's elk hunting. We were getting colder and colder and we had to have a fire. Everything was damp, including the squaw wood. We gathered a whole bunch of squaw wood, and then heavier blown down wood and got ready. I took out one of my flares and fired it up and placed the squaw wood on top. Pretty soon, the wood was burning and then the larger wood, until we had a good fire.
We were able to continue cleaning the elk. We also cooked some of the elk rib meat on sticks over the coals. Damned good, too!! Finally after piling snow on the fire to extinguish it, we gave our horses their heads and let them take us back to camp. I do not believe we could have started that fire without that flare.
Kinda the same situation up in the Sierra, except I didn't have a horse, and had to stay the night with my deer. I wasn't about to try and walk off that mountain in the dark with snow coming down. I made a rough camp against a fallen log next to a boulder. The flare started my fire and with all the wood I gathered, kept me comparatively warm through the night. (Yes, I ALWAYS have the stuff in my daypack to get me through the night, if I have to stay out.)
So, in a real emergency where nothing else will work, a highway flare will get your fire started. In 35 years I only needed it twice, but when I needed it, I REALLY needed it.
FWIW. L.W.