Well, let me say different way - EEPG updating pretty often, a few times per day;
SW in DVR handles the process correctly, using append/purge function to cut old record and add new.
No reboot required to maintain EEPG DB inside DVR.
But it doesn't happen by itself.
For one thing, a tuner is needed to get EEPG data. My DVRs are always turned on, and so both tuners are buffering.
There is no way for EEPG data to reach the DVR on a normal basis.