Dear questioner, thank you very much for your important question.

Allah has explained the wisdom behind revealing the Quran in stages. He says:

And [it is] a Quran which We have separated [by intervals] that you might recite it to the people over a prolonged period. And We have sent it down progressively. [Quran 17:106]

Allah also said,

And those who disbelieve say, "Why was the Quran not revealed to him all at once?" Thus [it is] that We may strengthen thereby your heart. And We have spaced it distinctly. And they do not come to you with an argument except that We bring you the truth and the best explanation. [Al-Mu’minun 25:32-33]

The great exegete As-Suyuti said in his book “Al-Itqan fi `Ulum Al-Qur'an”:

“If it is asked, what is the reason for the Qur'an being sent down in parts and not as a whole like the other (divine) books? We say: “This is a question which Allah Himself has answered, as He says: {And those who disbelieve say, "Why was the Quran not revealed to him all at once?"}, meaning “as the revealed scriptures were revealed to other Prophets before him.” Allah answered them saying: {Thus [it is]}, meaning “We have sent it down at intervals so that {We may strengthen thereby your heart}” meaning “to make your heart stronger, because if the revelation is renewed at every incident, then this is more firm for the heart and more caring to the receiver.” This requires frequent descent of the angel and him meeting (the Prophet) every now and then, along with the message that is brought to him from Allah, and this makes him happy in a way that is impossible to describe.”

Also, among the benefits of the Qur'an being sent down in intervals is the facilitation of its memorization. Also, the abrogated and the abrogating verses occur by it, and by it there can be responses to both people's questions and incidents that take place, so the answer comes by revelation of the Quran. There is also much other wisdom.

Please keep in touch..

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Source: The answer is excerpted from Islamweb.net with modifications.