(.. .and limited default time sync accuracy in AD Forests with Server2016+ servers...)
More than any other, the most often asked question of the Windows Time Service is "How do I configure w32time for high accuracy?"
The short answer is that Server2012R2 and prior releases do not support high accuracy time synchronization because the primary aim of w32time service in these releases is to keep the time in sync in AD forests to allow Kerberos to function.
Bob Drake has taken the time to answer this question over at the Ask the Directory Services Team blog. You can read his post here: http://blogs.technet.com/askds/archive/2007/10/23/high-accuracy-w32time-requirements.aspx
We have made improvements to Windows Server 2016 to support high accuracy time. See https://aka.ms/WS2016Time for more information.
If you deploy an AD Forest with Server2016 or newer OS and with default settings, you will see much better time sync accuracy in the environment when compared to an AD forest comprising of nodes running older OS releases.
However, the default AD settings for w32time on DCs remain unchanged in Server2016 and are still aimed to satisfy basic AD functions as well as the Kerberos requirements. These settings do not necessarily give you the highest possible time sync accuracy. You need to use the w32time settings specified in the above link to realize the best possible accuracy in your environment.
Note: The title and content has been edited to clarify the current state of support for accurate time sync.