Most of my day hikers and multi-night backpacking trips made over the years have been done solo, thus far without ever needing to be rescued. Before each recent backpacking trip I've left my wife a note with my prospective itinerary and a date and time for initiating a search if I haven't yet returned home. Doing that takes a little time, but it gives me some peace of mind.
And, hiking solo I perhaps tread more slowly and carefully on rough patches of trail than is the case when I'm hiking with others. I accept the fact that hiking, like the rest of life, includes acceptance of some risk, but I frankly would prefer not to find myself dying alone, stranded in an out-of-the way place after accidentally becoming badly injured there.
I've never been to Joshua Tree, the National Park in California from which Claire Nelson was recently rescued, but I find her story, linked below, both riveting and cautionary. Apparently Claire survived thanks to a combination of good preparation (prudently carrying lots water and appropriate clothing into a desert environment), clear thinking even after being injured, luck, and timely high tech rescue efforts.
http://www.bbc.com/news/world-us-canada-44310788