Why primary-source status does not settle cruiser performance

Should primary sources be treated as unquestionable authority?

No. Their claims still need checking against other evidence, and different eyewitnesses can describe the same event differently.

Even well-organized primary records can produce figures that deserve further examination. Some Crown Colony-class cruiser speed figures appear difficult to reconcile with other figures, the ships' hull forms, and their reported achievements. This is a reason to investigate the discrepancy, rather than a replacement speed calculation. Eyewitness accounts also differ because observers experience the same event from different positions.