spiritdogs
I think that people are missing two important points. Firstly, if you do a lot of conditioning, it is unlikely that your dog will not recall even if confronted with something running by that he wants to chase. But, that does take a lot of up front work, and you must condition the recall in lots of different locations with lots of different distractions before ever having the dog off lead.
I getcha. The dog isn't coming back for the treat anymore, he is coming back because it's all gone Classical. Like Pavlov & His Amazing Dribbling Dogs. So they are at the point where they come back because it's kinda ingrained... it's just what you do.
So.... do you wait for it to become a classically conditioned response before taking off the long line? Is that what you mean about removing the lead too soon?
spiritdogs
Secondly, you do NOT have to use toys or play. A reinforcement is something the DOG wants, so it pays to know what your dog values most.
Most of the time, what my terrier wants, is go to and play. So I make a point of releasing him to go and play almost immediately, as often as possible. Usually means a couple of "dummy runs" on our walks, where I recall "for no reason" just so I can praise him up and let him go again, and I can't do it if I am recalling him AWAY from something dangerous, or getting too close to a road for example.