Lippert Axle Grease?

Thanks for the explanation, Outbound. I do indeed check the hubs on the trailers at a stop. I will follow the manufacturer's recommendation for the RPod greasing and repacking, and, while I have greasy hands, do my utility trailer at the same time, from now on.

Question:
Why is it necessary to "recommend[s] an annual bearing removal/cleaning/repacking of the axle bearings" for a trailer that in essence travels probably less than 5000 miles every year on dry, not salty or sandy roads, with a single axle that allows differential individual movement of the wheels and bearings (that is, there is no side to side or angular torque on the bearings when going around a corner) and that weighs less than the tow vehicle that tows it?
The same recommendation is on my 10 year old 5x8 foot utility trailer and was on a 14 foot boat trailer I had. Both never have had new or repacked bearings.
Besides the trailers, I have owned more than 15 vehicles in my life, many with life spans of over 100,000 miles and I think I replaced one wheel bearing and never repacked any of them.
Is this recommendation a question of manufacturing quality differences between cars,trucks and trailer components or is it like changing engine oil every 3000 miles, self protection and collusion?

  Great job there TIDALWAVE of answering the question on how it works.     I still think that cleaning, a good inspection and repacking the bearings by hand for those that travel alot of miles evry year is wise.  Goose

'Outbound' asked how can the grease get to the rear bearings of a SuperLube hub if the old grease comes out of the front bearings?  That is what the Zerk fitting is for.  Lippert axles sent me the engineering schematics for the SuperLub hub when I asked them the same question:
The hub has a central tube running from the zerk fitting into the rear of the hub where new grease is spread into the rear bearings and then forced around the central structure forward into the front bearings and then out towards the cup.

IMHO, yes.