IMHO that's either the navigator not knowing any better, or wishing he was the driver, or just being a jerk. The navigator's job isn't to focus on the nitty-gritty, that's what the driver is doing. The navigator should instead, since he's free to think more and look around, keep his eyes on the bigger picture. If the navigator is more skilled or experienced than the driver, then the navigator should be that much more patient and respectful.