Answer:
The Principle of Specificity in Training.
Step-by-step explanation:
Specific goals are mandatory when you train, otherwise you won't improve at all. According to the principle of specificity, we need to focus in those skills we plan for, this way we will dedicate our energies in that specific goals. No having such goals will become a disaster because we'll be training unfocused, training everything and not improving anything.
Moreover, the purpose of this principle is to practice and train a specific skill, because practice makes perfect we could say. Specificity is mostly used in high competitive levels, where not having goals means that the athlete will be worse, becoming an uncompetitive player.