Seems like the only time I have to tear down and overhaul a 3 speed hub is when I teach classes on the subject... in the real world they rarely cause any issues.
I think the last time I had to crack open a defective hub was when adventurepdx's old 50's AW hub sheared the pin that holds the main gear and we ended up swapping the guts from another hub instead of rebuilding the old one.
Improperly set drive side bearings can also cause hair pulling grief but once adjusted smiles usually ensue.