Is it recommended to recall all intentions related to an act of worship in order to obtain all the rewards, or is a single intention sufficient for that?

The Prophet, may Allah's prayers and peace be upon him, said: "Actions are but by intentions, and every person shall have what he intended." The rule concerning the combining of intentions is that if their basis is intertwining, like the ghusl (definition) for Friday prayer and for janaba (ritual impurity), or if one of them is not independently intended, like the prayer of greeting the mosque alongside a fard (obligatory) prayer, then this does not invalidate the act of worship. However, combining two acts of worship that are independently intended, such as the Dhuhr prayer and its regular Sunnah (definition) prayer, is not permissible.