As the guys have mentioned. Some of our cars can eat bearings at a rate of about one a year. Which seems pretty much in line with your experience. I found that Advance Auto stocks Moog and gives a 3 year warranty on them. Add in a discount code online and I've bought as cheap as $60. Being that I got it cheap, it hasn't gone bad again.
As for torquing the bearing... in my experience and having a mechanic buddy that has done this his whole life, the spec means nothing. I thread the nut a few turns on and zap with an impact being driven by 150 psi of air. Gun is rated at 500ft lbs of forward torque. When the nut stops, it's the proper torque.
