You can do under 24 hours running a full team though RDF, at level, with tank,healer,3dps. I have done it twice now. First time took me longer, I stopped to sell and afk'd a lot and still did it in not much over that first time as well. First time I RaF'd was way back in wotlk, and then it took longer because when you got to wotlk dungons, you only had access to a few dungon quests. Now that all the quests are inside there as well, its A LOT faster than before.