I think an idea that might work while still make people use the job that they're putting the exp on is just increase the amount of exp you get. The "Stored" exp gives a buff lets say you banked 1m exp and while youre leveling you get the additional exp till it depletes. So a job that would normally get 500 exp gets 1,000 and now you have 999,500 exp left before the buff depletes. This way the person still has to "learn" their job to level it, but they get done faster. Honestly I dont think cutting the number of dungeons/fates needed to level in half would make people any less skilled then they would have been anyway.