What is deemed insufficient regarding headlight use at night?

Failing to turn on headlights at dusk is considered insufficient because headlights are crucial for visibility during low-light conditions. Dusk presents challenges in seeing and being seen by other drivers, making it essential to use headlights to enhance visibility. In many jurisdictions, including Iowa, it is legally required to have headlights on from sunset to sunrise to ensure safety on the road.

In contrast, while using high beams in all conditions can lead to visibility issues for oncoming traffic, the evaluation of “insufficient” in this context focuses specifically on the critical need for headlights at dusk. Using low beams in thick fog is actually the recommended practice as high beams can reflect off the fog and impair visibility. Having one headlight out does pose a safety risk, but it is also considered a mechanical issue rather than a failure to follow the legal requirement for headlight use at critical times like dusk. Thus, the correct answer emphasizes the importance of activating headlights during dusk for safe driving conditions.