Day and night continuously; doing something relentlessly around the clock. Emphasizes prolonged or nonstop activity.
締め切り前で連日連夜の残業が続き、みんな疲れている。
With the deadline approaching, we've been working day and night and everyone is tired.
コンサート準備でスタッフは連日連夜働いた。
The staff worked day and night preparing for the concert.
その事件は連日連夜ニュースで取り上げられた。
That incident was covered on the news day and night.