Comment by ianburrell

Most places that need accurate time get it from GPS. That is 10-100 ns.

Also, you can use multiple NIST servers. They have ones in Fort Collins, CO and Gaithersburg, MD. Most places shouldn't use NIST directly but Stratum 1 name servers.

Finally, NTP isn't accurate enough, 10-100 ms, for microsecond error to matter.