It does not only sync your current time and date, but also sync the actual clock speed.
That means that after some time that you have enabled it (and are connected to the internet) your clock will be very precise even if you stay disconnected from the 'net for long times.
A NVRAM(or PRAM on older, Power PC-based Macs) stores certain settings.
And your time gets corrected every time you open your Date & Time Preferences because probably opening there initiates a manual syncing of your time with the server. Anyway, in order to reset your NVRAM: I could see resetting NVRAM clear an incorrect time zone, but as far as it affecting the timekeeping and ability of ntpd to keep the clock from diverging from internet sources - there's a lot of missing links between what's stored in NVRAM and how time gets set.
Especially since the system goes out and self-corrects while running by opening the system preference pane.
Have you modified your network settings and preferences in any way? I would try changing from time.to one of org/en 's URLs.
I am having the exact same problem - clock drifts by minutes a week, but immediately syncs properly when I open the clock preferences panel.
The culprit seems to be a new with Maverisks daemon called "pacemaker", which in classic Apple fashion is under documented and does not appear to behave in accordance with what little documentation there is.
FYI - I'm not a fan of relying on the PATH variable in either Launch Daemons or cron jobs.NTPd (used by Mac OSX) will sync at the speed it thinks is more appropriate - that depends on your clock skew.It will be more frequent when you first turn it on / connect to the net and then will connect at longer intervals when it has stabilized your clock enough.Are you thinking it's getting messed up at boot time perhaps? Apple knows about this: I've spent hours on the phone to them, providing them samples and files galore.It may be a carry over from i OS ("Back to the Mac" whether or not it actually works).I have my Time Zone correctly set and "Set Date and Time Automatically" is checked in my Date & Time system preferences. I have rebooted, checked and unchecked the box to set the date and time automatically and neither seems to have helped. and its accepted answer by grgarside provided a lot of helpful troubleshooting help.