The Short Version
The evidence neither cleanly confirms nor refutes this sweeping historical claim. While match records suggest the All Blacks' dominant 2013 season and other periods likely included wins over all Rugby Championship and Six Nations opponents within 12 months, no authoritative source in the available evidence explicitly documents such a rolling sweep. Claims that the feat was achieved rest on inference from match logs rather than direct confirmation, and the absolute 'never' framing cannot be verified from encyclopedic summaries alone.