debade, in the situation in this photo by doug, i would never ride in the middle of the lane, the speeds are too high and you would be creating a very dangerous and annoying situation for vehicles, and yourself.
I only ever do that in much lower speed situations, such as in certain urban situations.
+1
Especially at stop signs. In the photo above the group is approaching a stop sign and are going to make a left turn They check for traffic behind them, and signal that they are going to take the lane. They are just starting to take the lane.