I'll repost here.
Not the best person to ask since I'm not a big grinder, But personally a small book like menu kind of like wondrous tales WITHOUT the RNG element of dungeons/trials/overworld zones to go explore/clear to get the necessary materials would be good. Anywhere from 15-25 sounds good to me, and the story behind why those areas/dungeons has to be tied into some BS about how the materials are special to this zone and why they are needed to make such a powerful relic so I don't feel like they are just sending me out for the hell of it.
However, and this is opinion, to me relics should be lengthy to get because I believe they are special weapons and most normal people should get one for their main because of how hard they are to procure, that's what makes them "relics" or very special weapons. Alt jobs and such should be fine with tomestone/raid gear or someone can just be crazy and put the effort into multiple.
What they shouldn't be imo is something so easy to get that I wonder if manually gathering the mats and crafting a market board set takes longer. Because, those are run of the mill armaments, and not special..
For extra points every time you complete one or a few of these items you can go back to gerolt and embed them into your weapon, like if you have to get a gem for the weapon in X dungeon, imbue with power from X trial, you can go to Gerolt and just have him put it in for a whopping 2 ilvl increase or w/e % correlated to ilvl you have completed with the visual changes on the weapon, like the Hilt gets the gem and now it shows.
Its detail oriented but I think it makes it more immersive to see the changes happening if you're into progression and not bulk hand ins.