I don't have any particular evidence that this is actually true, instead of just noticing patterns in randomness, but something that feels like it works more often than chance is commuting right after 09:00 or 10:00, on the theory that a significant number of commuters have deadlines on the hour, so traffic might be less immediately after the deadline. It's not completely reliable, so I'm skeptical that it's real, but it also makes a good enough excuse to get me on the road earlier than I would otherwise, so that's nice.