If you really find the leveling rol takes too long to que go do PotD. Takes much less time to get in and you don't even need to worry too much about not having tanks or healers if it happens.

That said I've been doing level rol for some of my lower level jobs and it doesn't take that long usually to get in. As well as your first time through each dungeon you are guarenteed extra exp for each first run. Your challenge log can give quite a bit of exp even if it feels boring, AND completing it all will net you a lvl 50 ring in Gridania (I forget the name of the NPC though). Doing FATES while waiting on Leveling Rol can also work, do some Leves if you wish. Find that to actually be my favorite way to do 45-50.