I grease mine once a year just prior to the first trip of the season. Been doing that, and only that, for 3 campers for over 12 years with no other problems. Some people I think go overboard by repacking; unless it is "heavily" traveled in salt and water, I don't see the need. Repacking trailer bearings are more for boat trailers being exposed to submersion or heavy loaded(usually overloaded) long haul trailers usually not pertaining to campers IMO.
2013 Jayco Eagle 324
2007 Dodge Ram 2500 Cummins
2016 Ram 2500 Cummins Outdoorsman