Couple comments.
1. I thought this thread was about trucks. I generally have to rotate far less on cars and 2wd trucks with pavement princess tires.
2. I did qualify rotating as needed and based on tire wear.
3. Not all tread cupping is a result of misalignment or bad shocks. Plenty of it is a result of style of tire (staggered tread tires like mud tires being the worst), driving habits, load, type of road and type of vehicle. Tread feathering and eventually what I'd consider cupping is virtually inevitable on any steer tire with an open shoulder. Big truck guys like some of you know that, whether you try to play it off of not (scooby). Or did I miss the boat on why heavy highway steer tires are always close shoulder tires, despite the disadvantage they provide traction wise? Nope, it's because they last longer.