Doug has said this several times, and I honestly expect that a lot of other writers and trainers would private agree, but fishing in most cases is just going to be entertainment. It's a time killer unless you are short rations.

For a big enough kit, the extra bulk and weight of a couple of flies and line appropriate for them is pretty small- a small mint tin and maybe 2 or 3 ounces? If you aren't hurt, just really lost and back so far that you're better off waiting to be found rather than trying to get out, you're probably using a vehicle anyway. So long as you pack it next alongside more conventional fishing gear and a gill net, sure, why not? Cut a reed fly rod, and after you've got your wood in and shelter and signals set up, kill time until found.