You can be overpowered, but Mantras become more expensive and hard to master, so grinding really is grinding.
Dungeons will last a few hours early on, but the last few will last you a day or so in each game, and the last one in game one lasted about 5 days, and I've been on the last one of game two for about 4 days now. It's very dungeon crawly, but the plot's very good.
