I don't pay any attention to average speed
during a ride, but I do track it and Strava sends me little graphs for segments and routes that compare speed over time. This data is interesting, and trying to
PR segments is fun, but in terms of training data I'm not sure speed is of much value. There are too many variables that can affect speed, and most of my segment
PR's occur when I'm either riding in a group, or have a massive tailwind, or happened to get lucky and catch green lights/no traffic, etc.