Why is it that repeatedly reciting certain Quranic surahs and verses is the cause of great virtue and reward, and reciting them once with contemplation and reverence is not enough to achieve similar virtue?

The repetition of reading certain surahs, verses, and dhikr (remembrances) is a Prophetic Sunnah that carries multiple wisdoms, including fostering contemplation and humility, and increasing reward and recompense. It has been reported that the Prophet (peace be upon him) stood (in prayer) repeating a verse until morning, and that was the saying of Allah the Almighty: "If You punish them, they are Your servants; and if You forgive them, You are indeed the All-Mighty, the All-Wise." (Quran 5:118). Moreover, repeated reading multiplies good deeds, for every letter brings a good deed.