The other day, I ended up speaking with someone who seemed to have done everything they ask you to do before getting into a meeting. He was well-prepared, knew exactly what to ask, and did so quickly and efficiently. It was my shortest phone-call.
I should have been happy with that, except I felt bad for him. I had probably given him less advice and information than anyone else I'd talked to. He had been so focussed in his questioning, he'd made it impossible for me to add stuff to the conversation, and give him more information.
The moral of the story: Always be prepared and stick to a script for a meeting if you have one. However, always be willing to deviate from that script or go with the flow. Chances are thats where you'll get the best information.