yes, my dog will always play games when i lose my patience, running and jumping and running some more. then again, i don't know if he realizes those limits - when other dogs knock at him for getting too intense, he just goes right back into it, sprints around with this stupid happy face and i am assuming he is thinking "yeah right, bark, hit me, bark bark at me! catch me now! ha ha ha ha!!!!!!"
or something like that.
What helped me is to ramp up the shorter sessions, tone down the longer ones. Nowadays it's like 3 really short sessions, less than 5 minutes each, and just random stuff in between all the time. It holds his attention much nicer, and he gets just as much out of it. and no matter where it ends, make sure you end on the best note - string together 3 great commands - sit, down, sit? awesome, end. heel for 60 paces? awesome, end. recall on first call, AND a sit stay? awesome, end.