When you are hiking in a canyon, where darkness comes upon one several hours earlier than it will if you are ohhhh, sitting oh, on that plateau, where you currently temporarily reside.
When you look at your FitBit (your only watch) and see that it is 4:30 and you are still hiking INTO the depths of the canyon and think, hmmmm.
When you look to your left to see the sun dipping below the tops of that magnificent red bluff/mountain and you can already feel the chill when the sun disappears/sinks. (In this photo you see no sun, as it has already sunk below the ridge to the left. The black sections are water dripping over the surface, thanks to the recent rains and snows.)
When your dude, aka Man, looks at you like you are deranged when you say, the sun will fully set in about 1.5 to 2 hours. (His watch has the correct/true Arizona time showing, he knows it's well over 2.5 hours till sunset.)
When an hour or so later, when heading down the canyon to Jolly, you ask, your dude, aka Man, what time does your watch say?? DUGHHHHH
When you realize that your iPhone is set for Denver Colorado time, NOT Phoenix time. And, realize, it did not matter till that saving time thingy took affect - -
When you realize, it really does not matter much, you are retired, what time zone ???
As long as you are out of that canyon before it gets dark, cause the only flashlight you have is that iPhone.