i have only one time taken mine apart
i do grease em before each trip for good measure. i lift the wheels off the ground and turn em and listen for bad signs and adjust the breaks if needed, check for wobble, etc.
IMO i think the every year breaking them down is asking for unneeded maintenance, my rig is very well maintained other than tearing apart wheel bearings and seals.
i have towed heavy boats and trailers all over this great land for many years and never removed em to repack, i always used the nipple and forced out the old grease. only tore em apart if the seals failed, and this was surprisingly very few times for the boat trailer which got dunked in saltwater ALOT
I am sure i will catch some flack,
my engineering back ground prevents me from "inspecting, taking something apart" something until it breaks. the odds of putting it back together wrong and loosing a wheel are pretty good, unless you do it all yourself and have the skills. I trust zero mechanics unless i watch, sorry but most technicians aren't paid enough to CARE, or they get in a hurry...
the AL-KO axle site states to remove and inspect em every year so i would if i were you, ( the lawyer answer)