There seems to be a bug in materia growth. I killed a boss that yields 100,000 AP. I equipped some triple growth items to master a bunch of materia, but it doesn't seem to be working correctly. I did several experiments, all with the same outcome.
Cloud was equipped with a Precious Watch (shown as triple growth). In it is an Osmose (170,000 AP to master). After the fight it has gained 103,392 AP (
), with 66,608 to go.
Tifa was equipped with a normal growth armor with an HP Absorb (100.000 AP to master). After the fight it has gained 34,464 AP, with 65,536 (2^16, but that may be a conincidence lol) to go. Well, at least the 34,464 is consistent with 103,392 / 3.
So my next thought was that maybe AP is shared over the three characters, so I did the same with 1 character dead. AP gained is exactly the same. So I did another test. I went to the crater and fought a dragon. He yielded 5,700 AP. I checked the Osmose materia on Cloud, which was now at 120,492 AP (so 103,392 + 3*5,700). So triple growth seems to work as expected, and AP is not shared.
Anyway, now I'm stumped. Any insights?