Gohan High School arc wasn't by Toriyama at all. Anything
after Cell, didn't have Toriyama hand in it all.
Incorrect. You're thinking of GT. Toriyama did write both Great Saiyaman and the various Buu Sagas.
http://dragonball.wikia.com/wiki/Dragon_Ball_%28manga%29The confusion comes in because:
1) Toriyama had intended for it to end a number of times, but kept working on it anyway because of how succesfull it was.
http://www.kanzentai.com/trans-daiz02.php?m=10&id=interview#link"Toriyama: I initially thought that I'd end it after they finished collecting the dragonballs."http://dragonball.wikia.com/wiki/Frieza_Saga"It has been speculated that the original Dragon Ball creator, Akira Toriyama, originally intended to end the series with the Frieza Saga, with a major symbolic event which would provide closure to the series. However, despite some fan response that the series was losing momentum, the popularity of the series was high enough that the series continued. "2) There is not a one to one correlation between manga and anime. Manga takes longer to produce, and since the anime was being produced at the same time, occassionally it outpaced the manga. When this happened, filler material was created to give the manga time to catch up. Most notoriously, the Garlic Jr. saga:
http://dragonball.wikia.com/wiki/Garlic_Jr.
"Garlic Jr. is the only villain, outside of Dragon Ball GT, to not be in Akira Toriyama's original manga and have an entire saga named after him. He is a brainchild of Toei Animation. "So yes, there is material that appeared in the Dragonball Z,
the anime, that was not created by Toriyama and didn't appear in
the manga, but Great Saiyaman and Buu both
were in the manga written by Toriyama.
Specifically:
http://dragonball.wikia.com/wiki/Manga"Story arcs
* Goku arc (chapters 1-134)
* Piccolo Daimao arc (chapters 135-194)
* Saiyan arc (chapters 195-241)
* Freeza arc (chapters 242-329)
* Android arc (chapters 330-420)
* Majin Buu arc (chapters 421-519) "...both sagas are part of the Majin Buu arc.
Quoting also from
this interview:"Q: And then the Cell arc ended. Did you think that everyone felt you would put Gohan into the leading role?
A: I intended to put Gohan into the leading role. It didn't work out. I felt that compared to Goku, he was ultimately not suited for the part."That's specifically Gohan's High school / Great Saiyaman saga that he's referring to.
And the Frieza saga wasn't the longest saga in DBZ. It's actually the second shortest, with the Buu Saga being the longest. But the 3 Saga aren't terribly different in length. Frieza Saga is 24 percent or so the series, where the Cell Saga is about 29 percent and Buu Saga about 32 percent.
http://dragonball.wikia.com/wiki/Episode_Guide * Freiza is the arch villain for Namek, Captain Ginyu and Freiza Sagas. That comprises 99 out of 291 episodes. 34% of Z.
* Cell is the arch villain for Imperfect Cell, Perfect Cell and Cell Games. That comproses 55 out of 291 episodes. 19% of Z.
* Buu is the arch villain for Majin Buu, Fusion and Kid Buu sagas. That comprises 60 out of 291 episodes. 21% of Z.
Granted, during Namek and Captain Ginyu sagas, Freiza isn't personally fighting the Z team, but he is running around genociding planet Namek, he is coordinating the Ginyu force, he is there and he's obviously the lead villain. If you want to narrow it down more precisely, Freiza's appearance isn't until episode 8 of Namek saga, titled appropriately,
The Ruthless Freiza. But even so, 92 instead of 99 episodes out of 291 is still 31%, half again episodes more than either Cell or Buu spent as villains.