I did some research, and if the next set has the season 6-10 premiers, then there are, by my count, at least three sketches that get repeated in multiple episodes throughout the set, at least seven sketches that were released in volume 1 (I feel like I counted 12, but I can't remember what some of them are), and at least eight sketches that have already been released on video or DVD outside of the Old School sets (two of which were also released on volume 1 in addition to being on other videos).
If not every episode on this next set is a season premier (and I really hope that episode 666 is included, as that's Roscoe Orman's first appearance as Gordon, has a skit from the first test pilot, has a Roosevelt Franklin skit, has the original What's the Name of That Song? and includes Rodeo Rosie), then I hope that Olivia's debut episode is included. That episode wasn't shown on Noggin (unless she was just introduced in one scene in an episode that Noggin showed but chose to cut for time, and if that's the case then it's odd that her debut would be cut).