Quote Originally Posted by Niwashi View Post
In some cases you need both stuff from your current level plus stuff from previous levels as well, though. As a level 50 Weaver, for instance, I'm still using cotton fairly often, which I've been using since around level 10. Alchemist still keeps using level 1 quicksilver all the way into Heavensward recipes in the mid 50's.
While this is true, you rarely need them in such large quantities that getting them is a terrible burden. For example, a recent item set upgrade I made for some classes I was leveling through the mythril stage took 2 iron ore... and 81 mythril ore. One of them is a quick warp and a couple whacks, the other takes considerably more time :P