Is the rapid recitation of the Qur’an during memorization and revision, which might affect giving each letter its due and observing the rules of Tajwid, still qualify the reciter for the reward of "a letter for ten good deeds"?

If the reciter reads the Quran with hadr (speed), sincere in his recitation, and this speed does not compromise the articulation of letters, alter their diacritics, or neglect the madd and ghunnah, then we hope Allah will reward him. However, if he falls short in any of these aspects, he is sinful, because Tajwid of the Quran is an absolute necessity, and whoever does not perform Tajwid of the Quran is sinful.