Matt 6: 7-9 And when you pray, do not heap up empty phrases ( vain repetitions) as the Gentiles do, for they think that they will be heard for their many words. Do not be like them, for your Father knows what you need before you ask him. Pray then like this: Our Father in heaven, hallowed be your name
I think you misunderstand the warning against vain repetitions. Context is always important.
Even denominations that pride themselves on not using the same prayer repeatedly, always use the same prayers repeatedly. They just repeat their own words rather than inspired words.