There was a comment in the encapsulated topic that raised, in my mind, two questions unrelated to the encapsulated post. I understand this post will have no interest to those that would never buy a stamp with a cert, but the answers might be helpful to some.
1.Would you seek a certificate if you acquired the item at a "named" collector auction and the item has no certificate.
2. What is your year cut-off for obtaining a new certificate if the item already has a certificate?
I acquired this CSA 61X3 Nashville provisional at the "ERIVAN" collection.

The stamp's color was described as brick red. I requested a Civil War Philatelic Society certificate as (a) there is no issued certificate and (b) I am a terrible at accurately judging a stamp's color.
I recently bought two items at the Gross sale with 1980s certificate. I did not request new certificates for those items.
So, after many words we return to the original questions. Thanks for your thoughts.