A Head of Demand
Location
Required Items
Rewards
What the allowance actually buys
One allowance here buys 339,520 EXP, which places it 3rd of the 3 Lv 70 Armorer tradecraft leves that record EXP. The best of them, Shielding the Realm, returns 565,870 EXP for the same allowance, 67% more.
On whether to wait: the best Lv 72 Armorer tradecraft leve returns 698,030 EXP per allowance, 23% more than the best on this rung, while the Lv 68 rung behind tops out at 681,530 EXP.
At Lv 70 this data holds 27 leves paying EXP across 2 categories: the 24 Tradecraft ones average 433,208 EXP per allowance, the 3 Fieldcraft ones 1,302,824 EXP, which puts this leve 22% below its own category's average.
Deepgold Helm of Fending ×1 is a Lv 71 Armorer recipe, 3 steps deep through 4 intermediates, costing 19 units of raw material and 33 crystals.
Handing that in returns 17,869 EXP and 73 gil for every unit of raw material the order swallows, and the tree needs Armorer, Blacksmith and Weaver.
The record carries a repeats value of 2. This site reads that as 2 further turn-ins on the same leve — an assumption, because the source data defines no meaning for the field — which would put the ceiling at 1,018,560 EXP and 4,161 gil for the 1 allowance it costs, or 1,018,560 EXP per allowance.