How effective are fire drills in preparing people for an emergency?

I’ve been through more fire drills than I can remember but the last one I experienced made me think about how effective these drills are. It took us about 30–40 minutes to get 40 people to move 4 floors down the building.

Once the building next to the one I work in caught on fire. There was black smoke everywhere. Workers from one of the lower floors were forced to evacuate. At the ground floor, the fire door wouldn’t open. One guy had to ram the door with his shoulder because the door was wedged shut. It was just before that point however that people were pretty close to panicking.

So how well do you think fire drills prepare people for an actual emergency situation? I’m firmly in the “having fire drills is better than not having fire drills” category but I think if there were an actual fire in my building, it might not go very smoothly.