PotD was done with the idea that each set of 10 floors would take you around as much time as it takes to clear a typical dungeon. That's why floors were 4-8 rooms in size (prior to 3.4) and are now 3-whatever (haven't done it floor 21+ post patch). Its to cater to those who want to get in, get those ten floors done with minimal killing, and move on to something else.

That despite the obvious (to me, at least) fact that plowing through, rather than sneaking through, results in more Silver Coffers and in characters strong enough to handle later floors. Ever seen a 54 tank try to tank level 60 mobs, on floor 41, without a healer? He'd have been fine if he's tried to keep his level up and entered 41 at 58 or higher, and tried single pulling. As it was, he could not even tank *one* mob. Anecdotal, yes - but no less true for being such.