Ramadhān is specific for the Qurān. It is the month that the Qurān was revealed in.
“The month of Ramadan in which was revealed the Qur'an.” (2:185)
Due to this, it is upon the Muslim to increase in the amount of attention he gives to the book of Allāh in Ramadhān, recitation and reflection of the Qurān.
Usually, many of the people in the beginning of the month are enthusiastic. They start reciting, and then they slacken on the recitation. This is not befitting for the Muslim. Rather, what is befitting is to increase his care for it and increase his concern for it and that he puts forward for himself an agenda and this is more helpful for him. Either an agenda in how much he will recite or an agenda in what times he will recite. Either or.
So he specifies a time and commits to it and makes it the time that he recites.
Moreover, some worshippers designate (time) for their recitation from Fajr till the Adhān of Ẓuhr and is committed to that with his specific Muṣhaf from Fajr till Ẓuhr. Maybe he’ll stop to fulfill some of his needs.
And other times as well.
In summary, he designates from his time whatever he is able to and commits to the time he designated for the Qurān or that he designate a specific number of Juz’, commits in completing it everyday along with striving his soul on its contemplation.
(This is) a Book (the Qur'an), which We have sent down to you, full of blessings that they may ponder over its Verses, and that men of understanding may remember. (38:29)