Oh, give thanks to the Lord, for He is good! For His mercy endures forever.
Repetition as prayer
A repeated line gives the faithful a place to join. It also allows the heart to catch up with the words. The first time may be hearing. The next time may be understanding. The next may be prayer.
This pattern is deeply biblical. Psalms repeat refrains, Scripture repeats mercy, and the Church repeats the words that train repentance and praise. Repetition is one way worship becomes memory.
What repeated phrases teach
Repeated phrases often name the heart of the moment. Lord have mercy teaches dependence on God’s compassion. Alleluia teaches praise. Amen teaches reception. Seasonal hymns repeat names and titles of Christ, St. Mary, angels, martyrs, and saints so the Church remembers the works of God in them.
The repeated phrase is therefore a tool of formation. It gathers the people into one prayer and gives the mind, voice, and body time to receive what the Church is saying.
This is why repetition can be strong teaching. The Church does not depend on novelty to form the faithful; she returns to the words that heal, confess, praise, and give thanks.