The weekend before last I made a 70-something mile ride on a rainy day, and so ran the Knog Road 2 and matching Road R tailight in low power flash (which uses both lamps) and Chase mode, respectively, for the entire ride.
Moving time was right around 4 hours, total time with break stop (the only time I turned them off) and flat fix stop and map check stop, was about 4hr 40min.
The headlamp gave me low power indication with just a few miles left to go, but did not shut down. Rear was running strong.
So, just a data point/FYI for anyone wondering if they can trust stated burn times on these lights: yes, in my experience.