I wasted my time with FF6

[Clyde Arronway]

continuously doing the same works after a point will still cause strength increse, just very little. That fits with leveling up: levels grow in required exp. exponentially

Also, terra is after all (spoiler) half esper. She is magic incarnate. the rest are as powerful as all the espers the party recieved. Absorbing all the magic doesn't mean much. Remeber also, unless you use the espers to increse stats at level up, your charectors, unless they are using the innately supernatural atma, cannot do very much damage singlehanded.