Using different geographic zones, for the NTP pool in the "Simple" example, is no longer best practice.

[PatrickJScruggs]

There's no citation, but according to the NTP pool Wikipedia article, "Work is being done to make the geographic zone selection unnecessary, via customized authoritative DNS servers that utilize geolocation software."

And according to the pool's official page on geographic zones: "In most cases it's best to use pool.ntp.org to find an NTP server (or 0.pool.ntp.org, 1.pool.ntp.org, etc if you need multiple server names). The system will try finding the closest available servers for you."