If RNG is on there side they can fully gear in a week. But this has been the case with gearing in Wow since its release and isn't exclusive to LFR.
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The Coin isn't a 100% chance on loot...
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Ok then once again in wrath TOC dungeon made Naxx,OS,EoE useless and then ICC dungeons made Uld/TOC useless.
They even added valor to dungeons as a reward and you could buy tier gear.