Oh yeah, about that, it's one dungeon in which every second encounter is one of them, only downside is that they're capped at level 50 and so I wouldn't call maxing normal levels "easy", it still takes quite a long time grinding up. That's the reason I stopped at mid 70, because it just starts taking a while to level up and normal levels are barely worth any stats anyways (every stat +1 at level 70+ is less than a 0,5% increase). It could be that once you reach level 90+ the stats are getting really good increases though, as I saw a video of someone at level 97 and that persons Ichi had almost 300 more hp than mine.
Job ranks always give good increases though, and once you can easily level those, the stat increases you get through certain thresholds are actually pretty nice, and seemingly carryover to other jobs, especially the ones that give you defense up are pretty helpful.