@Nemesis What I meant was
"Maybe Weekly Jump doesn't really allow veteran authors that previously published in their (Shueisha's, o even other seinen magazines) seinen magazines.
"Maybe Weekly Jump doesn't really allow veteran authors that previously published in other magazines. But they allow popular authors that have been published in WSJ before, but not popular "outsiders"."
Basically Jump mostly publishes rookie authors, and or authors that had had a hit in Jump previously, in contrast to the example I gave of Sunday having pretty successful authors like Minoru Arakawa post-FMA, or the Claymore mangaka... or now that I think of it Magazine also having the mangaka that made Soul Eater or for example Magazine also publishing Oh Great's Air Gear. Also, Masami Kurumada being published in Champion's main magazine (I think Saint Seiya Next Dimension runs in Weekly Shonen Champion, right?)
So basically
ALL the other main weekly shonen magazines have published authors that have been popular before, but I couldn't find a single author that was published (debuted) in Weekly Shonen Jump that had had already been successful or known.
Like, don't you think it's a bit strange that Oh Great which was already published in a Jump magazine made a weekly serialization with another publisher? It's almost as if there's a policy of Weekly Shonen Jump not allowing authors that have already published seinen or are already recognized...
The one exception I can think of are "artists" (As in artists that get paired with an author that creates the story), for example, the artist for Dr.Stone, but other than that, do you remember ..
After finishing this post another author came to mind, Mizuki Kawashita mangaka of Ichigo 100%, she started as a Shojo artist but was told by Shueisha her art would appeal more to boys so she did Ichigo 100% in WSJ.