cappt
Indeed, the transmitted figures whether it be by ATIS or ATC can be hours old. More recent can and will be totally different.
Some wind can nicely polish ice patches with resulting braking action figures at zero within a short period of time.
Tailwind and contaminated runways are a big no no in my opinion. There should be a thorough evaluation of the weather situation together with braking action and aircraft performance.
Personally I would like to see the aircraft being able to perform within the limits one category below the reported braking action. The PIC is responsible for the ship after all. This is emphasized by ATC reporting estimated figures since a few years.
There is some excellent guidance material from the Nordic countries.