not certain but I think that's flawed. i'm pretty sure no dungeon gives you what you've basically said is 90% of a level in a single run. (from 10% to a hair away)from the ding) even with absolute max rested bonus.
if levelling dungeons threw that much exp out per run people wouldn't have been doing pvp for a million exp a pop.. because one run of doma castle would have thrown them 6 million esp (90% of there level)
also the exp bonus at the end isn't the same either. think you only get a couple of hundred k for clearing doma castle for example....
Truth be told I've never paid enough attention to exactly how much any dungeon gives per level but i'm pretty sure it never adds to that much and pretty sure you don't get the same 1.8mill reward for doing titan story at the end of something like doma castle..