Recently Blizzard has been restarting servers with a 15 minute warning due to a problem with temp. Weapon enchants. These shutdowns can happen at any time but work like clockwork on Tuesdays. (I wonder why)
Of course when the server resets all the mobs have been resetting as well.
To my point: I was soloing SFK for low level greens to DE and had just killed and looted Agrugal when the server reset. A minute later I was able to log back in. When I did, I was still at Agrugal but, but he and the rest of SFK had respawned giving me a second attempt for loot. This time he dropped what I really was after, the Assassin's Blade.
With a 15 minute warning about the server shutting down you may be able to quickly get to an instance and do a stealth run for double loot from a boss in under 2 minutes.
-not mine-