I think 50% of the tension is the music. I swear in some episodes (like 15, the one where Michael dresses up as a guard), I'll be sitting on the edge of my seat and constantly go "OMG, OMG, OMG!" and afterwards I'll be like "WTF? Nothing really happened." :D

It's like almost any episode is equally exciting while you watch it and afterwards you have a bit of a chill down period and only then you can truly think about whether it was a good or a bad episode. Because during and right after you are on such an adrenaline high it's really hard to judge anything sanely.