I think people are undervaluing this skill quite significantly. The main skills we have to increase yield are King's Yield/Blessed Harvest and the Ward skills, both of which cost 400 GP. We have one-shot skills to increase yield for a single mining/harvesting attempt which cost 100 GP. At 200 GP, this skill guarantees crystals at every gathering attempt, regardless of what you're gathering. That means if you're gathering crystals, you get your normal yield plus extra crystals on top. In Lakeland i was getting a consistent 2 crystals on top of the normal 1 for the node, equalling Ward skills or King's Yield in terms of efficiency.

If anything I think this skill demonstrates how weak the ward skills are. They need a serious upgrade in my opinion.