Random note on SB aethersands, prob applies to HW as well, but it seems like there's a difference of yield between +5 and +6, but yield seems to be the same between +6 and +8, instead increasing HQ rate.

So +5 would be min yield NQ, +6 would be optimal yield if you don't care about quality, +7 optimal yield with low HQ rate, +8 optimal yield with very high (max?) hq rate.