You're playing, you're excited and enthusiastic, cheering your pup on, congratulating him for each new achievement. The puppy quickly learns that this is a two-directional game. With daily repetition of the game, in very little time you can progress from a single, short toss down the hallway indoors to tosses of 20 feet and beyond in both directions out of doors. As the dog matures and develops, you can introduce a variety of other skills using this game. The dog develops a love affair with the ball, toy or hose that can be effectively used during later obedience training on the field.
Some dogs quickly learn to anticipate the second hose and drop the first hose too early.
You then apply motivational direction to the game. You gradually increase the pressure on the dog to deliver the toy only when and where you command. This takes a certain amount of time and patience and is influenced by the temperament, drive, and trainability of the dog. As in other aspects of motivational training, you are simply shaping shaping behaviors to refine a particular skill. Same with two hoses.