There is power in repetition.
A key phrase or term of art used repeatedly in a work can become a totem, a mantra. A key phrase repeated can set a tone. "Winter is Coming" isn't merely a statement about the inevitability of the season; it establishes a state of mind.
A key phrase repeated can be an anchor for a piece. It can bring the audience back to a starting place, remind them of a specific character or moment. A key phrase repeated can elucidate a key theme or characteristic. "Resistance is futile", including the repetition itself, tells you everything you need to know about the Borg.
A key phrase repeated can be a revelation. In early repetitions, it can seem to mean one thing, but when it's presented in a new light, the meaning of the phrase transforms and explodes. Some writers can really make this work. Playwright Kirk Lynn is a master at this technique.*
But it's also a very easy thing to mimic in format without giving it purpose. Anyone can repeat a key phrase. The question is, why are you doing it? What are you trying to say with the same phrase, repeated? Does its repetition ground or enlighten?
Too often I've seen the form mimicked without understanding. The line kept being repeated and I kept waiting for the turn, for the revelation. Never came. Again, this tended to be in plays rather than fiction, but the fundamental truth of it still holds. I think there is a misunderstanding that the act of repetition alone gives the work some sort of mantra, and with that a degree of depth. But its use is hollow, and it comes across as pretension instead of depth.
Not that I'm immune to the occasional repetition of a key phrase. Hell, how often to I say I'm off to the word mines? Which is where I need to be getting to. So I'll see you down there.
*- Kirk's a master with regards to writing in general. If you have a chance to see a Kirk Lynn play, run to it like a ravenous cheetah, and bring friends.