I always thought it was just like an email set to future send in say a week or 2, then every few days or every week you go in and bump forward the date.
I always heard a Dead Man’s Switch defined as a switch which goes off once you stop pressing it. So you just set up something to go off in the future, then for as long as you’re alive you keep preventing it from going off.
Yep, false positives are a problem for a dead man’s switch.
Two weeks without being able to get internet access or word to a friend is definitely possible but seems pretty unlikely.
You could make it more than 2 weeks out but I think that’s a good middle ground between avoiding false positives and striking while the iron is hot, you know? Imagine sending an email beginning “if you’re reading this I’m dead…” and having recipients think “Yeah, that was ages ago.”