Is it permissible to read parts of the Holy Quran from the Mushaf during a supererogatory prayer, and to audibly review (recite) during daytime prayers such as Dhuhr and Duha, with the aim of solidifying one's memorization?

It is permissible to read the Quran from the Mushaf during supererogatory (nafilah) prayers when there is a need for it. This has been reported from the Salaf (early Muslims); for instance, Aisha used to be led in prayer by her freed slave, Dhakwan, from the Mushaf. Ibn Shihab said that people reading from the Mushaf during Ramadan has been continuously practiced since the advent of Islam. The Sunnah is to recite silently in daytime prayers and audibly in nighttime prayers, and deviating from this is disliked (makruh). However, this dislike is removed in cases of need, such as to perfect one's recitation of the Quran or to solidify one's memorization. Thus, it is permissible to recite audibly in daytime supererogatory prayers to reinforce memorization.