Nearly ALL of the walk-ons this year were Novices (beginners / first time in cosplay). We also were trying very hard to enforce the rules about keeping the walk-ons short and only a few poses. If your walk-on is going to be more than that, then you're better off entering a skit (besides, that makes you eligible for another prize...so entering skit & costume really is the best way to go).
Rules have been essentially the same year to year - only a few changes have been made, mostly based upon requests by either the directors or the entrants.