There going to be lots of discrepancy on this but doesn't changes the facts.
A spindle has to be in very bad shape in order for it to effect the bearing. The inner bearing race does not turn on the spindle it sits stationary, unless the spindle is worn badly because the bearing failed and it spun on the spindle. You can tell this by simply sliding the bearing over the spindle and give it a spin and wiggle it and see if there's any play in it. If you have proper tension set on your bearings the bearing will be seated on the spindle and not turn. Same goes for the hub, the hub has nothing to do with the bearing it simply holds the outer race, change the race its new. Unless the hub is warped from extensive heat but very unlikely. Anybody that pulls their bearings apart 3 or 4 times a year is doing something wrong. I would say in the case of your trailer eating bearings your doing something wrong your either over tightening or under greasing the bearings a new trailer won't stop this if you continue to service it wrong. You should be changing all the races and seals every time you pull it apart. If you keep your bearings greased properly there's no need to change bearings more than every 3 or 4 years. I haul my boats many miles a year, I drag mine 1400km one way every summer out to the coast and hundreds of miles down gravel roads and mud every summer and would never think about changing bearings more than every 3 or 4 years. If the tension is set properly and they are kept full of grease no contamination can get into them. I don't care if it's salt water, dust or fresh water, if it's full of grease nothing can get into it. I have never in 30 years of owning a boat on a trailer had a bearing failure, not once.
Now flame away lol.
