You are supposed to but there was a story about it working in a canyon after a car crash 400ft down (https://www.macrumors.com/2023/07/24/iphone-14-saves-man-at-...) saved his life and I’ve shared location and just tossed it down on a picnic table in a forest and it eventually sent.

It definitely makes it connect faster (a min or two) vs the 10-20 it can take when you don’t

I’m impressed and it’s nice to have that additional level of safety

If the skies are clear and the phone falls of the car it shouldn't have any problem reaching a satellite.