Anyone exiting a crashed airliner carrying any item of clothing or hand baggage in their hands should be arrested and charged both with endangering the safety of the other passengers and disregarding the lawful instructions of the crew
This should be told during safety briefing before takeoff and written on safety cards.
Airbus have published performance data based on contaminant depth and now aligns with airport reporting of braking action based on type and depth of contaminant. Many airports have changed to this type of reporting
Reporting of braking efficiency should not be subjective e.g "Medium/poor", it must be regulated based on type and contamination, especially for the types with tail mounted engines due tail-blanking. Also, the reverse thrust vector tends "to straighten" the trajectory, which is good only if it is aligned with runway.