I almost wonder if it’s the triangulation of cell towers (assisted GPS) at this point

No that wouldn’t be it.

The way GPS works, it takes a 12 minutes for the satellites to send enough data to calculate your approximate location. And note I said “send” enough data. Your device might not receive the data, especially since GPS is designed for very large (basketball sized) antennas mounted up high on top of a military ship surrounded by open seawater with no buildings, trees, car roof, etc for the radio signal to bounce off.

If your device already knows it’s approximate location, then the satellites are continuously sending data to calculate your precise location. So… with cell tower triangulation (or even better, wifi triangulation) to calculate an approximate location then Assisted GPS should be able to figure out where you are in a few seconds as long as you’re not surrounded by sky scrapers or in a tunnel.

Even if A-GPS isn’t available, your phone will just assume you are near the location you were last time it calculated your location. As long as you haven’t just hopped off an interstate flight that should work fine too.