It seems like the only effective way is to farm lower greater rifts (20-25) and rush to the GR guardian. Is this what other people do or is there something else I can do? I'm trying to help gear up the other members of my group.
My understanding is GR's have better legendary yield, but T6 speed clears net you more experience. So if legendaries are more important than paragon I'd focus on GR's you can clear with relative easy. Also you can focus on gem upgrades which are a guaranteed/known upgrade.