I don't rush, I take my time and fully complete things before moving on. But here is the thing, even when spending enough time to fully loot 8 Sunken Crypts in the Swamps and killing any Wraiths I see, I still ended up with less than 20 Iron Chain on my over 100 hour save file.

Fully upgrading my Black Metal Shield which costs 11 Iron Chain nearly wiped me out, and I've only made two Hanging Braziers in my whole save file. I have now ONE (1) Iron Chain left over. That's it. Over 100 hour save file and a single Iron Chain left. That is even after spending FIVE nights in a large Swamp biome trying to hunt Wraiths—two nights I didn't find a single one, two other nights one Wraith each and I had a single night where I managed to find two Wraiths.

I don't plan on making the Black Metal Tower Shield but if I was, I'd have to grind my ass off to scrounge enough Chain. If you don't want to make the Chain craftable, then please make Wraiths more common and/or Iron Chain more common in Sunken Crypt chests.