I think its a grand idea, LEJOG, everyone does that!!
When I go away I use an Android app, 'Real Time GPS Tracker 2' on my mobile phone. My wife checks where I am every day on her laptop and If I haven't moved for say 12 hours, she would just assume that I'm in trouble. In 2015 when I hiked the GR10 across the Pyrenees my 'charity sponsors' used it as well, I didn't want them to think I was sunbathing on a beach somewhere. It also gave them a greater interest in me as well, I wasn't 'out of sight, out of mind' so my donations went up!
I also carry a Pebbell alarm around my neck as well which in an emergency can be used as a mobile phone as well.
They have never been tested though, so far I've never had a 'good enough' problem to worry about. I've fallen over, (more than once) I've slipped down banks, (more than once) I've had a few bruises, I've been attacked by a cow, have been 'ransacked' by pigs, I've sat on an ant nest and have run the gauntlet of wasps, but nothing more than that.