There wasn't a cap before. People were practicing using that trick on JLo in prep for AV and then SE immediately had an emergency maintinence to nerf it.
The "real" trick to AV was to realize that Tanaka really was a sadistic enough asshole to expect us to fight AV for several hours before killing it. You were supposed to lock the 2 hours via using a matching one right after AV uses it and if you weren't in japan back then you probably needed to bot to actually do so fast enough.
After all of that is done you get to fight it for at least 6+ hours (as planned by SE on a SMOOTH fight) which noone could fathom since we didn't expect anyone to ver think that's reasonable for players. Shortly after it accidentally got slipped that several hour fights were legitimately what was supposed to happen and then PW drama came out to force SE to nerf AV's hp to a more reasonable level.