To OP : remember that Atmas are only one step in the relic progression, and having an atma weapon is required to unlock everything that follows : Grinding books (and soldiery) for your Animus, then Alexandrites (which is roughly 1/day, and you need 75 + a lot of materias/gils), then you have the Light grind (which is IMO the worst part, because even if the progression is not based on RNG/gils, it still melts your brain), and finally (up to now) more soldiery grind/dungeon grind for the Zodiac weapon.

The longuest part is the Alexandrite, because unless you farm A LOT of soldiery, you'll need 2 months and a half to get a Novus. However, you can 'unlock' the alexandrite grind with your first relic, and then use those on your second one.