In 5552 I added a lua function set_clock to set the camera date / time.
I did a few tests with going to play, set_clock followed by a reset once a day and later once a week and those all worked out perfectly on a 64GB card.
the only thing i could see in the log was that it skipped 2 lines before resetting the time.
it was already skipping 2 lines on reboot, so that made the "set clock" stand out in the log.
so I decided to place it in my running project that reboots after 3 weeks on a 256GB card.
alas it did not work.
because i did not put the proper chdk build on the card, it was still running 5172.
so it halted on the CHDK menu without going past set_clock to the reboot.
human error....the most annoying thing
is there a way to check build number without loading it in the cam?