I've heard that the most cost effective use of Crafting is to Craft items of your level. But the amount of the item's Price that you shave off with every additional day scales with your own level, not the item's level, so I would think that items of a lower level would be preferable because there's a higher chance of getting a critical success. But then I considered the 4 days that need to be invested to attempt the check in the first place. Those days aren't spent towards lowering the Price, so I guess the idea is to lessen the frequency of needing to invest those days so that more days can be spent lowering the remaining Price of the Crafted item.
However, the remaster buffed Crafting by now requiring only 2 days of investment, or a measly 1 if you have the formula, which isn't even necessary anymore. Does this change the math significantly? Is it better to Craft items of my level or lower level items?