Applying the rules shows that the choice depends on relationships, not word counts.
1. “Inna al-abrar ... wa-inna al-fujjar ...” — Two thematically contrasted reports: wasl.
2. “Fawaswasa ... qala ya Adamu ...” — The second explains the whisper: fasl.
3. “Za‘ama al-‘awadhil ... sadaqu” — Answer to an implied question: fasl.
4. “La, wa-shafahu Allah” — Wāw prevents negation of the prayer: wasl.
5. “Qalu inna ma‘akum ... Allahu yastahzi'u bihim” — Quoted speech and divine statement have distinct scope: fasl.
The decisive question is: Does wāw reveal the intended relationship or create an unintended one?