Thats the beauty of having so many options. Level your first and some of your second with quests, then do some fates, then do dungeons.. and by then, you should have about enough leves to get an entire lv.50... then alternate fates and dungeons however you see fit. always log out in a sanctuary.

you shouldnt be able to burn through 3-4 jobs in a month anyways, you SHOULD be slowed down. but thats an issue in itself.