حَضَرَ الضُّيُوفُ: الْعُلَمَاءُ وَالطُّلَّابُ وَأَهْلُ الْبَلَدِ.
The guests arrived: scholars, students, and townspeople.
When the audience needs to know the groups involved, the elaboration is a useful expansion of the summary. If the only aim is to announce arrival, the enumeration could be unnecessary.
Good iṭnāb depends on the value of the additional detail, not word count. Nor does every enumeration automatically become tawshīʿ; that term has a more specific structural pattern of initial summary and subsequent distribution.