This is (or was) a dog who was always responsive, who would spin on a dime to return to me even while chasing a bird, or heading to play with a new dog.
So here was my first hand experience with a well trained, but under-exercised dog. Unless they can run off their excess energy, it is very nearly pointless to attempt any training outside of the house.
Because Kiara is already trained, it's relatively easy - a few days of full on running with Giro at our safe local off leash park should get her back to her normal self.
For many other dogs, a lack of exercise often starts early in life. Owners who aren't confident about their ability to get their puppy back, don't let them off leash. The recall is never trained, somehow the dogs is meant to know how to return to his owner when he gets older. When the dog does get off leash at some stage, it runs wild and of course doesn't return, no matter how many times the owner shouts at him to come. The vicious cycle continues, the dog gets let off even less, or never at all. The lack of exercise makes him near impossible to train, and may make him more aggressive, withdrawn or fearful, depending on the dog.
So unless you own a chihuahua, which may get sufficient exercise from just walking with you (although even a Chihuahua enjoys his freedom), you need to find a way of giving your dog sufficient off leash exercise, before you can even begin to think of training him (and recalling him) anywhere but in the house.
This seems to be a contradiction - you can't recall your dog, so you need to let him off leash, so you can train the recall. But you can break the vicious cycle. Here are some tips for how to exercise the dog that doesn't come back.