I'm of the understanding that if someone has been retired for 10 years or longer with rated disabilities, they are not subject to reductions of ratings. The process is designed to weed out those with temporary disabilities. In my case, none of my ratings will ever get better with age.
This might be a newer policy from after 911?
I don't know how this applies to non-retired or medically-retired vets.
My understanding is any new claim filed, for new injury or increase in rating, opens the entire array of the veteran’s injuries to re-evaluation.
I have not heard of any of these being a new C/P exam. Just a re-evaluation of current disabilities under current guidelines. (Note Tinnitus has been or will soon be evaluated differently than in the past. There are details online.)
But mostly what you’re thinking about is the 10 yr rule and 55 yrs old rule. Those conditions preclude “routine re-examination for re-evaluation) and a new scheduled C/P exam. They do NOT preclude re-visiting your entire file if a new claim is filed.