Vince

With re-lube intervals of only 50 flights, I would expect no planet gear bearing wear issues at all in 300 flights. Re-lube intervals of 50 flights is probably about right if using the Hacker supplied grease, but way overkill with the Shell Stamina RLS-2 (or similar polyurea) heavier bodied grease. On the order of 100 - 150 flights seems about right with the latter.

The propshaft bearings should have a very long life unless solvent is used to clean the gearbox and also removes the lube from the rear bearing.

The gearbox end motor bearing is another matter, it's a pre-lubed bearing and seems to have a finite life and it can damage the end frame (or worse) when it fails. Regular replacement seems prudent.