If you frequently need to check time zones across various regions, a convenient option is displaying multiple clocks on your iPhone's Home Screen. You can do so using the World Clock widget.

Very large countries such as Australia or the USA are spread out across many time zones. Most smaller countries keep to the same time zone even if part of them falls outside a meridian line.

Time zones across the US. What states are in what time zones? Alabama: Central; Arizona: Mountain. Most of Arizona, with the exception of the Navajo Nation, does not observe daylight saving time.