Depends... (Not the Adult wear)
If you tow on dirt roads too Boondock, you will need to repack em more often.
If you frequently drive thru wet areas with some standing water... Same
If your RV is on asphalt or paving, you can go longer between maintenance.
I repack mine every 2-3 years.
If you buy a used RV, repack em, you don't know what conditions the RV has been thru.
(I just bought a 75 Prowler... I towed it home than repacked it the next day.
I also put new rubber on the road... Don't want to be left setting on the side of the road.)