You are dead on. I sat in a planning meeting with some other Willamette business people and one of the Bike/Pedestrian group insiders... and when the topic of average vs peak hours came up, the bike advocate seemed to have a hallelujah moment, and said "That's how we should present this!", referring of course to average traffic vs. peak. It doesn't matter if the "average" trip time increases by only 30 seconds, if your trip time sometimes increases by 5 minutes....