I don't understand why people aren't doing battle leves and FATE's in between waiting for dungeon queues? I leveled CNJ/WHM almost entirely that way and it was extremely fast. Obviously queues are longer for DPS, but just more time for FATE's. You can practically solo most of non-boss killing ones like 'kill so many of blah' or 'bring these items' blah.

I made a goal to do every dungeon with each class I was leveling at least once, and it's given me a lot of great perspective/skills. No one is asking you to do Sastasha 40,000 times.