Depending on a cell phone can be problematic. Especially so in areas that are devoid of cell towers such as National Forests and back roads. Smartphones become dumb phones without a nearby tower.
I have had a GPS logging app record that I had moved on foot over 20 meters in fifteen seconds from one hill to another hill, then back in the next fifteen seconds. This is not a rare occurrence, I smooth these anomalies out by eliminating the errant readings from the spreadsheet.
Currently, AZ is MST (UTC-7) and CA is PST (UTC-8).
When DST is in effect in CA, and not in AZ, then CA is PDT (UTC-7, same as MST) and matches AZ time. But then the weather is hotter, which is fine for Paris Hilton.
I have a Polar heart rate monitor wristwatch that is still set to MST, that I had last used in October 2021 when I had appointments in Los Algodones.