Current Best Experience Gains

As some people here said: Training is boring, at high levels it gets even more boring because it requires too much time grinding to get some poopy %. True that you gain 5 AP that will increase your range, but for most people the amount of work they have to put into lvling to get that 5 AP is really not worth it.
Most bossers prefer to cube to increase their ranges and get some exp while bossing (it is fun compared to mindless grinding).