Why do I have to deal with stupid people, day in day out, pretending they're experts in English when they have no freaking clue what they're talking about?
I have to work the fields day in day out to make ends meet.
Day here means the whole day of 24 hours, not just day time.
Day out does not mean night time.
Therefore日復一日is correct. It does not have 貶義 at all.
日以繼夜means working hard through day and night. It does not have the meaning of 'day in day out'.