Regardless of the fact that the time is displayed in five minutes period of time, all over the Word Clock there is a vastly precision real time clock system whom accuracy is extremely high.
Basically you can seted once and just enjoy how the time is changing on the display.
Thanks to the power back up, you can basicaly forget about setting it up. Internal clock can run for a days without external power source. Without any worry you can disconnect it and move it to another place where you will enjoy it.