Endwalker Exploration Zones

[Burningskull]

If you're farming DR for relics, then you're also doing the weekly Castrum/Delriada quests.
You get plenty of essences from just doing Castrum once a week plus whatever you grind out while you're waiting for Castrum to spawn.
You're also grinding mettle to gain valor stacks, in doing so, you may as well be gaining fragments while you're at it.

I'm afraid you are wrong. I'm not doing the once a week quests. I spam DR and that's it.