We found that the three per a day works really well. Our first year we tried four on a Friday night so judges had a shot at getting three sessions in and it was a disaster. The day was really long and it sucked the life out of the organizing staff.
We couldn't go this in depth during the presentation but there is a copy of the judging schedule for this past year. It shows how we did the early week night session (to kick out the cobwebs), scheduled three sessions per a day on Friday and Saturday, and how we scheduled flights (so not to blow out palates). Please pay no attention to the number of Stewards per a table. That's a combo of Stewards and beer runners.http://www.bbbrew.com/downloads/2014MidwinterTableSchedule.pdf
One thing that we failed to point out, we usually throw in some sort of incentive for those that volunteer to judge or work three sessions. Check out our Volunteer page under Beer & Mead Paired Dinner (scroll down). We knew we would normally have to feed folks so we took the money we normally would have budgeted for that meal and turned it into an incentive. http://midwinterhbc.com/volunteers
Attendees still had to kick in $35 for the meal, but everyone felt it was well worth it. We even got some folks to sign up as Stewards and Office Staff just so they could get the discount. FYI - The Sprecher APA and the MKE Baltic Porter got changed out at the last minute with Central Waters Hop Rise and Central Waters Bourbon Barrel Stout respectively. Folks were taking the ice cream that came with the deep fried apple pie and were making stout floats.