There is a lot to be learned from stewarding a table comprised of three or more high ranking judges. You can sit at the table at home and fill out a score sheet by yourself, or you can watch three people do it who have been doing it for quite some time and might find something to help you along. Most likely the stewards for the NHC final round will be BJCP judges with an interest in potentially discovering something new.
My thoughts exactly, Mike. If you haven't volunteered on the National level, do it. You won't be disappointed. I mean, unless you pull the likes of Susan Ruud & Al Boyce for your local comps, you'll likely be blown away by the amount of knowledge some of these judges have.
For example, I was at the Smoke/Wood table in 2012 with Randy Scorby (2011 Homebrewer of the Year for a Rauchbier). I picked his brain about all things rauchbier and when I got home I used his advice to brew the best rauchbier I've ever had. BOOM!