Ok here are the rules and to be honest I didn't know the 5 year rule...
5 year rule: If the rating has been in effect for 5 years, it cannot be reduced unless your condition has improved on a sustained basis (The VA must have documentation supporting this is a permanent improvement).
10 year rule: A service connected disability rating cannot be terminated if it has been in effect for 10 years. Compensation can bereduced if evidence exists that the condition has improved. The sole exception is if the VA can prove fraud, in which case the VA can terminate the benefits.
20 year rule: If the rating has been in effect for 20 years, it cannot be reduced below the lowest rating it has held for the previous 20 years. The only exception is if the VA can prove fraud.
100% rule: The VA must prove your medical situation has materially improved and as a result, you are able to perform substantial work