Originally Posted by
Khebul
So far only JC has throughput benefits in terms of 600 main stat gems. It is unknown if Blizzard plans to add similar things to other professions, but common oppinion is that they will do so.
The limiting factor in Legion crafting will not be "common" materials like leather/ores, but uncommon and rare ones. Uncommon materials like Felhides/Felwort/Infernal Brimstones are not BoP, but they are quite hard to get, so they will be expensive @ launch. There is also Blood of Sargares - BoP rare material which can be most effectively obtained through gathering professions and is the most difficult to get reagent.
Bloods of Sargares are used in almost every epic recipe, enchant or mount. They are also needed to make Obliterum Ash out of crafted epics. This ash is BoP. Every 100 dust can be used to make Obliterum - BoP consumable which increases epic crafted item iLvl by 5.
You obtain 25-35 ash per crafted gloves (using gloves as they are the easiest piece to make for me), so on average you will need 27 pairs to upgrade baseline 800 ilvl item to 840 one (this ilvl drops from mythic dungeons). Disenchanting each pair of gloves costs one Blood of Sargares, crafting each pair costs 2 bloods and 12 leathers. This tallies up to 83 Bloods and 336 leather in total.
Using two-star skinning skill you get about 25-35 Bloods per every 2000 leather you gather, and skinning is by far the most effective way of getting bloods right now.