Plutarch's error about older customs doesn't invalidate his knowledge of his own time

Plutarch misunderstood that in older times women weren't allowed to cover their heads. Elaine Fantham shows the original source (Valerius Maximus) actually says a woman was divorced for going UNcovered, not covered. But historians commonly err about earlier periods while being reliable about their own time. Plutarch was well-traveled in the Mediterranean during Paul's era and would have known contemporary practices.