They usually don't get the back bearing with much reliability. This causes a false security issue, making the person think that the bearing are properly greased when in fact they could be almost dry. Bearing buddies are good to keep some grease in the hub, but I wouldn't rely totally on them. You still need to repack the inner and outer bearing at least yearly, or more often if you are trailering lots during the year. It's good insurance to take a look at the bearings once a year at least, just in case something is starting to go bad. Can save a horrible breakdown on the side of the road, and more importantly get you out fishing instead of waiting for a tow truck or repair guy to show up.