What is seeding and how does it work? Pro/Con.
The pro/con aspect is an endless argument, and the how is available to compute yourself. But the "why" is interesting on several levels and and unending source of debate.
All the seeding is used for - ALL - is deciding on which of the 4 groups of fliers you fall in for the qualifying rounds. The qualifying rounds are essentially 4 separate contests held simultaneously. To move to the next round, you have to finish in the Top 5 of your contest. You don't care what the other 3 contests are doing or who wins or loses or what they score, it doesn't matter for purposes of qualification, only your contest matters.
With maybe 60 total entrants, you have to decide who goes in which contest. You could do it at random. Putting people in the various contests at random, eventually you wind up with one of the 4 contests with David Fitzgerald, Paul Walker, Orestes Hernandez, Derek Berry, Bill Rich, and Brett Buck all together in one of the contests, and a bunch of literal beginners in another one. Not only does one or more potential winners fail to qualify (which I don't care all that much about, i have to try to beat all those guys eventually anyway, so who cares if it's Wednesday or Saturday), but a whole bunch of others who might make the Top 20 get knocked out from that group. While on the other circles, other guys with lesser skills get essentially a free ride.
So, to prevent clumping up the hot-shots on one circle, for several decades, what has been done is to distribute the "name" fliers with demonstrated high skills between the 4 contests. That is SEEDING in the stunt world. Who flies in which contest has been determined various ways, but all amount to taking known hot-shots and spreading them out to make sure the 4 contests are reasonably even in terms of skills distribution.
I would also note that despite this, people have traditionally complained, bitterly, about "getting on the hard circle". I have been to all but one NATs since 1993, and even with seeding, someone has ALWAYS complained to me at some point about how they got on the hard circle and everybody else got the easy one. Many times, I have heard people complaining about each of the 4 contests as "the hard one".
Note that none of this makes any consequential difference to the ultimate outcome and goal of the contest, that is, to *select the Open National Champion*. Anybody who might be the final winner should be able to beat the rest regardless of the format or the grouping. It might make a difference in who comes in 19th or 21st, which is not the goal of the contest, but does matter to people so some effort it made to, essentially, cut down on the complaining.
After the 4 qualifying rounds are over, the seeding isn't used for anything at all. Once you have the top5 from each of the 4 qualifying contests, the Top 20 fly all together in a single contest. There are two groups but aside from random luck its irrelevant to the end result how you distribute people between the groups.
The other thing that you should know to understand the discussions is that, despite the fact that it both is done to placate people about getting the hard circle AND doesn't ultimately doesn't make any difference, people have been complaining about the seeding being "manipulated" to help various people by the people doing the seeding. Specifically, it was because various people on the East Coast complaining that it was done by Shareen Fancher to assist Ted/David/Brett/Paul and to hurt Windy.
Despite the fact that none of those people needed any help blasting through qualifying with all the drama of a practice flight.
Solely and entirely to prevent anyone from being falsely accused of favoritism, Paul and Howard came up with the current method. It uses actual NATs results from the previous 10 years and weights the finishing placement, and it is entirely free of subjectivity. People still complain about it, and misunderstand it as some sort of "National Skill Ranking" which is is not, and complain about THIS method because, say, I came in 3-4TH and 3 Time NATS and 3 time World champion Bill Werwage ends up 15th or something. That's because I attended essentially every year, Billy only showed up occasionally (and WON, but that doesn't offset the lack of attendance), not because I am "better" than Billy
So that is important backdrop. Seeding is almost a trivial problem that doesn't really matter and the various methods to do it are basically an attempt to find a relative minimum in the "chronic whining curve" and to protect the contest staff from getting nasty letters about cheating.
From any practical standpoint, you show up at the contest, they tell you fly on Circle 1 on the first day, and Circle 3 on the second day, and none of this matters or is even apparent unless you dig into it. The NATs is the best-run contest in the world by a large margin and what you see on the internet about it is nothing like the actual thing, you show up and fly the airplane when they say, and it's all taken care of in the most straightforward way possible. Brett