It might even take multiple tests to determine if a puppy has true dog agility potential. Think about it for a moment - not only can a one-time only test mislead you into believing a puppy does not have what it takes to train successfully, it could also lead you to believe that it is an agility "phenom" depending on the outcome.
Sometimes a puppy will display a characteristic one day that makes you feel he would adapt well to training, and then again it may never surface again. Who knows - if you base everything on the results of only one test then you may find later that your puppy just had a really good, or bad, day the day you tested it.
If you want to pick out a puppy for dog agility training, watch your prospects carefully - their routines, their reactions, how they play, etc. for signs of their potential. There are many things to take into consideration too such as alertness, the testing area, hunger, and more because the attention of the dog or puppy will be vastly different deoending on each of these factors.
You'll also want to choose a puppy that submits to your commands easily and doesn't fight back or make it difficult during grooming or mini training sessions. These are great ways to determine if your little puppy has true dog agility potential. If there is always one puppy who sticks out as first in line for everything the food or water bowl, the door to go outside, or the chance to get some attention from its handler then that's another thing to take into consideration.