Is the Imam's action of reciting two-thirds of Surat As-Sajdah and half of Surat Al-Insan during Fajr prayer on Friday considered a lightening for the worshipers while preserving the Sunnah, and will he and the worshipers be rewarded for that?

It is authentically reported from the Messenger of Allah, peace and blessings be upon him, that he used to recite Surah As-Sajdah and Surah Al-Insan in the Fajr prayer on Friday, and Surah Al-Jumu'ah and Surah Al-Munafiqoon in the Jumu'ah prayer. It is also reported that he, peace and blessings be upon him, consistently did so. It appears that this Sunnah is only achieved by reciting both of them in their entirety, and it is not appropriate to recite only parts of them.