Originally Posted by Sawtooth
In my opinion, average speed is an absolutely worthless figure. Traffic can be different from day to day. Wind speed can fluctuate greatly, etc. And average speed is absolutely incomparable with someone else's unless they are riding the same route at the same time under the same conditions.
I totally disagree if you are comparing your personal trends on the same exact commute every day. I track elapsed (total) time and computer (moving) time on a spreadsheet every day and it nicely trends upward, then levels off as I stopped going faster. Wind/lights/traffic all average out with very few data points.
When folks say average time doesn't matter, they are mainly talking about racing, where being able to burst for sustained top speeds is important to stay in the lead pack or the finish sprint. But the bottom line is that the person with the highest average speed wins the race, but in order to get that highest average speed one also needs the ability for getting near or at the highest burst and sustained speeds when needed.
Al