What are the virtues of completing the Quran more than once during Ramadan?
 

Ramadan is the month of the Quran. God says in the Quran: "Ramadan is the month in which the Quran, a guidance for the people and clear proofs of guidance and criterion, was revealed. So whoever sights (the new moon of) the month, let him fast it; and whoever is ill or on a journey—then an equal number of other days. God intends for you ease, and does not intend for you hardship, and wants for you to complete the period and to glorify for that (to) which He had guided you; and perhaps you will be grateful" (2:185).

"Indeed, We sent it down during a blessed night. Indeed, We were to warn (mankind)"(44:3).

"Indeed, We sent the Quran down during the Night of Decree" (97:1).

'Abbas (may God be pleased with him) said, "The Prophet (peace and blessings be upon him) was the most generous of people, and he was most generous during Ramadan when Jibril would meet him. Jibril used to meet (him) every night of Ramadan to teach him the Quran. Jibril would find him quick to extend his generosity—even quicker than the strongest wind" (Bukhari and Muslim).

Fatima (may God be pleased with her) narrated that her father informed her that Jibril (peace be upon him) would recite the Quran to him once a year, but recited it twice on the year of his death (Bukhari and Muslim).

The above hadiths demonstrate the preference of reciting the Quran and completing it once or more in Ramadan, and reciting it day or night in abundance though at night is better and garners a greater reward. God says in the Quran, "Night prayers makes a deeper impression and sharpen words" (73:6).

In a hadith Qudsi, God says, "My servant continues to draw closer to Me with supererogatory prayers so that I love him. If I love him, I shall be the hearing with which he hears, his sight with which he sees, his hands with which he holds, and his feet with which he walks. If he asks [something] of Me, I will surely give it to him, and if he seeks refuge in Me I will grant it to him. I do not hesitate about anything as much as I hesitate about [seizing] the soul of a faithful servant; he hates death and I hate hurting him" (Bukhari).

And God, the Almighty, knows best.