
Additionally, while in Nephalem Rifts, your countdown timer is based on the number of monsters slain. While in Diablo 3 originally there was a slight benefit for killing every monsters in the form of extra rolls on legendaries, with Loot 2.0, there is a built in system that ensures players get approximately 1 Legendary per hour, meaning that time spent on these weaklings is time wasted. Though in some cases it's unavoidable to face some trash mobs, you can quickly clear them out before getting back to your farming. Non-elite monsters make up the majority of what you'll be seeing in both Bounties and Rifts, but if you're on the correct difficulty (see above), it should be relatively easy to blow through these unimportant mobs to tackle elites and champions. A good metric for knowing you're on a good difficulty is being able to one shot trash mobs, allowing you to quickly plow through the unimportant monsters to get to what you actually care about- the elites.

Farm on a difficulty that allows you to quickly move through packs without needing to slow down or focus on their individual abilities. Taking on a difficulty that's too much for your character is a good way to cut down your farming speed substantially, and you'll increase your repair bill besides. So I think Forgotten Souls should not be the deciding factor, but rather what classes you have, if you have keys, and if you want materials or XP.When you're trying to farm effectively, don't try to be Superman. And low GRs are much, much, much better for paragon (order of magnitude better). That being said, Forgotten Souls are rarely the bottle neck - blue mats, white mats, even Death Breath is what I'm running out of.

Another advantage of T6 is that you don't need to farm trial keys/low level keys (or don't need an "opener" if you want to leech and re-use one key), and you can run almost any class and lots of builds (whereas for low GRs you really want nothing but monk+barb+2DH). I don't have actual numbers, but it's my subjective feeling. Full T6 clears can sometimes net you with 10-15 legendaries per run, especially if you get some goblins. I sometimes get 1-2, or even in rare cases zero legendaries from a GR35 clear, plus the rifts are so fast that you spend a significant amount of time waiting for the rift timer.

I still think T6 full clears are the best for Forgotten Souls. We've done some speed GRs (~35 in an average of 2.5 minutes, everything between 1:40 and 4:20 to completion).
