I'm getting in the habit of training 20 miles/day on MWF, and experienced group rides on TR, and a longer ride Saturday, with 1 rest day. On MWF, I try to average at least 20. But the experienced group rides are a lot different. Today was just my second group ride, like ever.. And I barely hung on. We were going down wind for the first half, going at least 27, and sometimes over 30. It's like a rotation type of deal, where the lead keeps rotating to the back. Today, as I was rolling toward the end of the pack, the second guy who lead turned on the turbo, and while I was slowing down, the group took off like road runner. I pretty much got dropped, and had to eat wind for a mile going 24 mph, until they finally slowed down again, and I was able to get back into the group, with my lungs at my throat. The dynamics of the group ride is reallly important, as well as tactics. At the end of the day, it's all great experience.

Yes, in a race, or any given ride, avg speed doesn't really matter. But I use it more as a benchmark to push myself.