I'm sure I read a couple of queries on threads about how to get dogs to retrieve more than 3 or 4 times... but now when I go looking to post this I can't find any of them . I have a stupid game I play with Zac that will keep him retrieving countless times though he will often only do 4-5 standard retrieves. It is no use for obedience nor for many tricks but if you want an efficient way to exercise your dog this might work... Basically I just chuck the ball as I walk. I throw the ball over my shoulder (check there's no one behind you first ), under arm, overarm, to the side, up high, low throws, a bounce, slow throws, rocket fast throws... he has no idea what will come next, I keep walking and he returns the ball to my right hand and then he dances along beside me 100% focussed waiting for the next throw. I tend to mix in 1 long throw to 3 short, that gives Zac some recovery time, sometimes we mix in some tricks on the move with the ball as a reward, I stretch out the time between throws to work on attention (he's learnt that looking at my face not the ball earns a chase). I have to say "enough" when I want to stop because Zac will play it for longer than I ever want to.