It gets even more interesting if you're tracking time while considering movement. First time I ran into this was timetracking aboard a ship that is at sea for multiple days. You can cross timezones repeatedly in both directions, the date line, can have a local start datetime that is after the local end datetime, etc.
You don't even need a ship to get into some real confusion.
Arizona is Mountain Standard Time, no day light savings.
Navajo Nation, which overlaps state of Arizona, is MST with DST (since much of it is outside Arizona, and that's more common).
Hopi Reservation, which is fully contained inside both of Navajo Nation and Arizona, is MST with no DST.
You can drive 35 miles from Gray Mountain, AZ (non-reservation) through Tuba City (Navajo Nation) to Moenkopi (Hopi Reservation) and experience noDST->DST->noDST in just over half an hour.
Continue southeast for 100 miles to experience a bonus noDST->DST->noDST->DST->noDST->DST transition.
If you rely on your phone's automatic clock adjustment, best of luck!
