You're not think about this the right way at all. Efficient leveling is NOT exp/instance. The correct way to judge efficiency is exp/time spent. Getting a trial in leveling roulette and then running a leveling appropriate dungeon is FAR more efficient than getting stuck in sastasha for 45 minutes with new players and getting negligible amounts of xp from mobs and roughly the same roulette bonus at the end.

Iftrit normal in leveling roulette is a godsend and something to celebrate.