re: bravely default much less vague spoilers
to clarify: we suspected Airy was lying about things pretty early on and so tried breaking a crystal in either the second or third world. turns out there's a finite number of worlds before you're forced into the true ending, it doesn't just loop. we'd assumed it would eventually just loop until you figured out Airy's plan and broke a crystal, but the true ending doesn't involve breaking crystals at all
or maybe it does, i don't know, but breaking a crystal when you're supposed to just activate it isn't the right way to get to it