on big fishing
boats we generally give half a turn every 3 hours.
over greasing will not do any harm,apart from grease landing in the bilge
in your case if running 24hrs i would give it a turn 2-3 times a day.
on shut down ,a few turns will stop water
leaking out,but you also might need to tighten up the stuffing box from time to time.
the greaser is generally for lubricating sterntubes with bronze