The prevalent collective Quran Khwani is a custom and due to many evils it is makrooh as it is mentioned in Fatawa Hindiyah:
ویکرہ للقوم أن یقرؤا القرآن جملۃ الخ
Collective recitation of the Quran is not proved from the Prophet (صلی اللہ علیہ وسلم), his companions and those who followed them. If people want to deliver the reward to dead (Isaal-e-thawabI) by reciting the Quran then they should do it individually as per their convenience without fixing a date and time, and deliver the reward to the souls of the dead.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband