Take one proposition: “Zayd is at home.” A neutral recipient who has no reason to doubt may need only a plain statement. A person repeatedly insisting that Zayd is absent may require a suitably reinforced assertion.
This is not a rule that adding more words automatically increases balagha. The degree of emphasis must respond to the addressee's stance. Unnecessary emphasis can itself violate contextual appropriateness.
Similar contextual selection governs definiteness, indefiniteness, omission and word order.