From Roleplaying Tips Weekly #477 by Johnn Four
Go here for the online version.
When Adventures Are Too Easy
by Kate Manchester
You spend hours planning and mapping out your adventure and sit down to begin the game session. An hour later, your PCs have managed to breeze through your carefully crafted encounters and handily win the day. And to add insult to injury, one of your players look at you and says, "that was too easy!"