I'd be on board for this if it were treated like a modified rested bonus. Something to ease the pain of leveling an alt job. It's bad enough as it is that you're looking at an absolute minimum of 6 dungeon runs per level (rested, plus bonus for being at level of dungeon, plus food). It's longer if you're on the one off level at end of a dungeon even with rested+food. If it were shortened a bit to say half the runs needed with this extra bonus, it would still force you to do a few runs to learn new spells/skills but not seem like a total chore to run the same stuff for the 30th+ time on a different job.