PN, in my early days (mid 70s) it was made very plain to us that disputing anything in the narrative or numbers would lead to a few one way interviews in best blues.
Ten years later everything was much more relaxed and comments were allowed, and IIRC, were even entered into the official record.
By the time I left in the 90s there wasn't much difference between the RAF process and performance reviews in industry that I was subject to.