I'm level 31 white Mage now, I wanted to level up the arcanist class to 15 so I could turn my Conjurer to a white Mage as quick as I could So I joined a party and I can't believe how much faster you actually level up joining a party to farm FATES. The best part about it is I actually quite enjoy doing it aswell it's not really mind numbing as you can't chat to people aswell.
glad you're enjoying FATE, but don't forget to try out Guildhest in your duty finder. It'll teach you the basics of skillful party play while being in a group. they're fun to do.