Well you can argue how often to attend to your wheel bearings, but consider this, while your wheel bearings may be good for a couple of years, you still need to pay attention to your grease seals and brakes! Every year you should remove wheel and hub, clean and inspect brakes, check your seals, replace as required! Now that you have done that, how much more would it be to clean, inspect, and re pack your wheel bearings? The big part is removing the wheel and hub, so again it may be a little over kill but you will have piece of mind that your good to go! A lot of brake problems can be traced to bad/worn seals along with to much grease! Oh and use a good synthetic grease!