Anyone out there adhere to the "new rig every six year rule?

I heard a similar rule, except it was called the three year rule, where you traded in your vehicle every three years. Great for car salespeople, but why spend money repeatedly on a depreciating item?

I am going to replace my current rig, as it doesn't suit my needs, and the next rig is intended to be my last RV unless things change fundamentally in my life. To do this requires a lot more cash than a "normal" RV, but it is worth it, since most rigs made after 2008 tend to fall apart well before the 10 year mark.