Class Hunting Logs are inefficient EXP gains. Amongst other issues..

[Cassandaria]

Also, to those of you saying; "They were for CLASSES not jobs!" - really? You did your rank 4 and 5 as an ARC/MRD/GLA and not as BRD/WAR/PLD? No, you didn't. You did them as a job as soon as it was possible. Oh by the way, Traits and pre-30 skills are also "for classes" yet they managed to fit them all into the new Jobs didn't they?

Actually, I did all of my hunting logs as my classes, not my jobs. There was no reason to push to the job when I wanted the extra challenge. In addition, the hunting logs are for small chunks of exp while you wait or while you explore. You are waiting for a dungeon pop, hit up a few log mobs, exp while you wait. It's not likely to level you, but it still makes a difference.
It was designed so that there is more than one way to level based on how you play, you want to grind to level by doing leveling parties with mobs? you CAN do it, it's not efficient, but you can. You want to quest grind, you can do that too! You want to run dungeons? That's there too! The exp system is fine for what it is, you can't look at any of these as a replacement for the other, they are another layer to enjoy, or not, all based on how you play the game.