[Faith]

My experience, I think both scouting in the pits and on the field is important. From the pit, talking to the teams, you can find out a lot about the robot. You can tell if they are doing what they want to be doing based on how frantically they are working on their robot, you can generally see how well they are doing by how excited the team is.
But field scouting also comes into play. While you can tell a lot from a pit, none of it is definite, and it is hard to compare teams directly. Having some hard numbers is great, because you can take the teams you know you want to pick and compare them more directly, make a more refined list. It also shows their strengths and weaknesses more clearly. In the pit, it is hard to tell how quickly the robot moves on the field. Is it easy to pin, or does it escape with an empty trailer every match? Pit scouting is great, and it makes it easier to tell who you want to work with, but it won't tell you everything. Field scouting is great, but without the background the numbers are hard to make something of.
I also agree with the Saturday morning refining of the list. You have to have 24 teams picked by Friday, because there simply isn't time on Saturday. But Saturday is a great time to watch the final matches, make sure robots are still working, and see who made an improvement that will bump them up on your list.