My goal in Tactics is to be 99 before the end of Chapter 1, usually, with all classes maxed out. The good news about this, as I'm sure you've noticed, the enemies level with you in random battles. However, the story line enemies remain the same. That's just me, personally. If I DON'T do that, I grind until I get my favorite classes, monk and calculator, and then breeze through the game either way.

So really, it's just how you play, how long you want to grind, annd if you feel like doing the skills glitch to make your life easier. XD