Timing
Advance first, collect missing medals later, and invest when the next farming node or campaign unlock justifies the cost.
Fall of Cadia is a medium-high early priority once Angrax, Archimatos, and Haarken are unlocked. It opens Chaos upgrade nodes, the three characters required for Fall of Cadia Mirror, and one of the game’s best mission-farming stages.
Advance through Normal even when a battle awards only one or two medals. Boss nodes for Kut, Sibyll, Thaddeus, Celestine, and Creed are more valuable than forcing every third medal as soon as it becomes available.
Return for all 225 Normal medals when Elite farming becomes the next useful account goal. Test Elite immediately after it unlocks, then stop at an efficient material or shard breakpoint if full completion would demand excessive campaign-only investment.