Hazrat Shaikh Moulana Muhammad Zakariyya (rahmatullahi ‘alaih) once mentioned to an ‘Aalim:

Undoubtedly it is important to fulfil your duties and obligations you owe to the madrasah. However, despite your busy schedule and commitments it is necessary for you to avail yourself for some while to recite the Quraan. Not reciting the Quraan is a great loss to a Believer. As for a haafiz of the Quraan, he does not need to look in the Quraan and recite; rather wherever he is, he can recite from memory. I observed some of my elders that they never left out the tilaawat of the Quraan. Even while travelling by train, I used to see them reciting the Quraan. (Qutbul Aqtaab Hazrat Shaikhul Hadith Moulana Muhammad Zakariyya (rahmatullahi ‘alaih) pg. 466)

Source: Ihyaauddeen.co.za