Question

Once a month

Could it be the people were childless, and used the cat as an outlet? Some people like this develop a sort of Munchhausen by Proxy about their animals. My aunt is like that. I love her to death, but no dog needs more than an annual visit, unless there is something wrong. She just has her dogs go because she thinks 'it's time'.

By all means, get the cat's records. And talk to a different vet. Sometimes, animal doctors will do unnecessary testing to assuage the feelings of the owner, when there is no need for it. Just like people doctors, you got a boat payment due, schedule some MRIs.