Something to test. Set your date format string to {debug} or {debug}{battery} or the like.
{debug} will show the event type that caused miniclock to update, (touch)screen, (butt)on, or update (freq)uency (with update=60 that's once per minute - if the device is not asleep).
So current theory is you get a lot of "touch butt" events even when not touching buttons or screens.
If not then it's something else.
# This update caused battery drain so I removed it.