I've been packing wheel bearings for around 55 years by hand and always put a LOT of grease in the space between the bearings (front to back). I have never had a bearing fail. Yes it might be a waste of grease but I feel the little cost far outweighs the chance of failure. the little grease on the bearings can melt off, sling into the void and have a bearing run dry. By having a lot of grease it can warm up and get back into the bearings.JMO. Another thought, why don"t they make bearings like they use in electric motors. Sealed. No grease necessary. Just throw them away. Would not have to worry about getting grease on brake shoes.