Only the Best

One allowance here buys 9,990 EXP, the best on the Lv 10 Leatherworker tradecraft rung — matched exactly by 1 other leve of the 6 there, with the rest trailing at 8,430 EXP or less.

Across that rung the return runs from 2,230 EXP to 9,990 EXP per allowance — 4 distinct figures spanning 348%, so the wrong pick leaves 7,760 EXP of the allowance unspent.

On whether to wait: the best Lv 15 Leatherworker tradecraft leve returns 18,910 EXP per allowance, 89% more than the best on this rung, while the Lv 5 rung behind tops out at 6,840 EXP.

At Lv 10 this data holds 52 leves paying EXP across 2 categories: the 48 Tradecraft ones average 8,265 EXP per allowance, the 4 Fieldcraft ones 43,676 EXP, which puts this leve 21% above its own category's average.

Gil ranks it differently: 170 gil per allowance is 3rd of 6 on the same rung against 1st on EXP, with the best there paying 172 gil.

Hard Leather Harness ×1 is a Lv 12 Leatherworker recipe, 2 steps deep through 3 intermediates, costing 5 units of raw material and 5 crystals.

Handing that in returns 1,998 EXP and 34 gil for every unit of raw material the order swallows, and the tree needs Blacksmith and Leatherworker.