In the early parts of the game, I found myself using auto-build a lot so I wouldn't have to worry too much about which arts or accessories to equip while still learning the mechanics of the game. Now that I'm progressing further into the game, and acquiring more powerful (and preferred) accessories and arts, I've found myself using auto-build less and less as the AI seems to be a bit flaky.
What exactly does the auto build feature consider when rebuilding your character?
From what I can tell, auto build will change up your accessories, gems, and secondary arts (I forgot what these are call, the ones controlled by the D-Pad), but not primary arts (the ones controlled by Y, B, X).
For accessories, does it consider stat changes rather than passive abilities? For example, equipping the Memory Locket (which allows non-healer roles to revive) is much more useful than +6 physical defense point.
For secondary arts, does the system considered how the arts would fuse together? It always seems to pick an art that reflects the primary art I have equipped.
For gems, I'm assuming it's considering the best passive boosts for that role.