Do the NTP minpoll and maxpoll configuration attributes control the sync interval or do they only control the polling interval?
polling = messaging with NTP servers to estimate the offset
syncing = actually updating the system clock
minpoll and maxpoll have to do with polling the rmote time servers. the "time synch" interval is controlled by ntpd itself. The clock adjustment algorithms are complex. More information can be found on Dr. Mills site. But the short answer is that unless you are a time wizard you do not want to be adjusting how ntpd manages clocks/drift. To be honest there are only a few situations where you should be mucking with min/max poll intervals.