Is it a condition to recite Surat Al-Baqarah all at once to expel devils from the house, or is it permissible to recite it in interrupted intervals?

There is no evidence that Surat Al-Baqarah must be recited at one specific time; rather, it should be recited in its entirety within a single night or day. This is based on the Prophet Muhammad's (peace be upon him) saying: "Indeed, everything has a hump (i.e., a peak or top), and the hump of the Qur’an is Surat Al-Baqarah. Whoever recites it in his home at night, Satan will not enter his home for three nights, and whoever recites it during the day, Satan will not enter his home for three days."