Why do Catholics repeat prayers?
A: Catholics repeat prayers because it is scriptural. It is only bad to repeat prayers or say any prayers or form of prayer for that matter if it is done in Vain. (1 Kgs 23:7)
If prayer is empty and one is a hyprocrite then it is wrong. The link below will cover this and more in detail.
Related link:
Why do Catholics perform rituals?
“Always be prepared to make a defense to anyone who calls you to account for the hope that is in you”
1 Peter 3:15