I’ve found that crystals by far require the most farming if crafting high level items en masse (for example, a single Rarefied Lignum Vitae Grinding Wheel + its materials takes a total of 7 fire, 7 ice, and a whopping 28 wind, according to GarlandTools). What I did was I took some time to set up custom nav grids in some fairly inconspicuous locations, and leave Miqo to farm with a rotation of Twelve’s bounty and Giving Land together. Also chugging cordials on cooldown. It still takes awhile if you’re farming for a few thousand, but it’s extremely efficient compared to other methods. Also if you choose good locations (as in, extremely irrelevant to most gatherers’ interests — i.e. mid-level zones without any gatherer quest items), you can literally go for hours without seeing a single other player usually.