I hunkered down after I got into Heavensward and against my better judgement, decided to make Ragnarok Zeta. It took about six days of genuine autism grinding, dusk until dawn, no brakes. It will put a hole in your gil wallet because the (((perfect))) materials are sold on the marketboard for 30k-40k each and you need 8 total iirc, and thats on top of the required 400,000 gil goldsink and the 80,000 Company Seal sink you need to afford Bombard Cores. Then theres the book grind step that comes before that, and if that doesn't give a normal person enough burnout to stop playing for a while, I don't know what will. At least flying in base game zones likely make that part nicer, but still. There are also two steps that practically require unsynced 12-24 runs in Tam Tara Deepcroft to "speedrun", each run taking 4-6 minutes depending on your level and gear.
Tl;dr don't do it unless you really have your heart set on a weapon skin.