Fifty Hail Mary’s on a rosary certainly qualifies as *repetitions*.
And since she’s just a human, she can’t answer prayer anyway, so it’s vain, a useless waste of time.
There is no “repetition” in Matthew 6:7. It speaks of “babbling” like the pagans, and explains that it is wrong to think that God needs many words. Of course we repeat prayers, — but they are meaningful prayers that remind us of the Holy Gospel, and often cite it directly.