I did 3 consecutive days with average speeds of 14.9, 15.7, and 15.4 miles per hour.
But that's moving speed. Including stops it was 13.9, 13.7, and 13.8 miles per hour.
Another way to measure speed (distance over time) is in miles per day, where it was 233, 185, and 207.
As one continuous ride with the clock running, it was 625 miles over 63 hours for 9.9 miles per hour.
Average speed doesn't really tell much of a story, all by itself.