All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
What is understood from this Hadeeth is that the devil may enter the house after the three (days or nights); therefore, if someone wishes to keep the devil away from his house all the time, he should recite Soorah Al-Baqarah every three (days or nights).
Among the other Hadeeth reports that mention the merits and virtues of Soorah Al-Baqarah and how it wards off devils and nullifies magic spells is the Hadeeth where the Prophet said: “Recite Soorah Al-Baqarah, for reciting it imparts blessing, abandoning it incurs grief, and the Batalah cannot confront it.” [Muslim] Mu‘aawiyah one of the narrators of the Hadeeth commented, “I was informed that the word 'Batalah' in the Hadeeth means sorcerers.”
The Prophet also said: “Do not turn your houses to graveyards. Indeed, the devil runs away from the house in which Soorah Al-Baqarah is recited.” [Muslim]
None of these Ahaadeeth or any of the other ones which we have found mention that one should read Soorah Al-Baqarah in one session in order to realize this benefit. However, if someone is able to recite it all in one session, then that is better than not doing so; otherwise, we do not see any objection in reciting it in more than one session.
Allaah Knows best.