I got some video today of how I exercise Dazzle every day that the weather is not too wet. I also measured the distance. It's about 190' when I use the entire yard, which means he's running 380' each fetch. I typically do 20-30 throws before he (or I) get tired or hot or cold depending on weather. So between 1 and 2 miles per session and often we do more than one per day. He's currently begging as I type this for another session!
Today was sunny and cool and after 22 throws, he wasn't even breathing hard! He has gained so much stamina, I'm not sure how long it would take in cold weather for him to get tired (as opposed to stopping because he's hot, which has been the case lately.) Today, even with the Chuck-it, my arm wore out before he did!
Here are a few more photos from the video. Link to the video is below: