Fair enough. I put mine on silent and have location sharing on and share with my wife. That way she can track my exact position in real time.
If I was to lose consciousness or the ability to retrieve my phone from my pocket she would see lack of movement.
I don't sit in high seats but if I am sitting for more than half an hour I usually get s text (on vibrate) to check im OK.
As close as I can get to fail safe without spending a fortune on a Garmin Reach or similar.