Honestly, this grind is no big deal considering that it is only done once. The problem moreso derives from the locations in which you can obtain them. When it comes to Occult, the SW section has 3/4 with only 1 CE that does it, 1 Pot, and then 2 FATEs that end fast. With how other areas spawn it is easy to be at a point where you are missing from 2/6 because of how the spawn rates work however at least doing the "open world" FATEs is a means to do it.

One thing I can't fathom with this relic grind however is that 1st part is a mix between doing it in Occult or open world yet the 2nd part which is the more time consuming one is pretty much Duty Finder only. With how little Tomes you get from Occult it is not going to players' first choice in obtaining the ores they need for their relic. I find it such an odd choice that they did not at least attempt to use silver/gold or even new drops appearing as an additional way to do the phase because as it stands Occult content itself is rather vapid in design.

A story that you can complete with minimal interaction with the content, and a 2nd phase grind that discourages you from using Occult as the go to method to complete.