If/when a client tells us that the "time" is off, we usually just pop into the server, and proceed with the following:
date
(Gets the date and time)
hwclock -r
(gets the hardware time)
This is to see how far off it is. (sometimes, its only a couple mins off)
hwclock --systohc
Syncs the two times together.
(Then as you said NTP)
ntpdate -u pool.ntp.org
Then rerun the first two, to make sure all is accurate...
That usually fixes the clients time issues.
(It might not be necessary to run all of that, but we do it that way anyways for better accuracy.)