I know I've seen something that described JJ2 as all taking place on one planet, but that's easily disproved by Flashback, and besides I don't remember if it was an official source or not. I know I've seen Beach associated with Lagunicus and HH98 with Holidaius, but that's always just speculation. JJ2 supplemental materials do make frequent reference to Carrotus... the Prima Strategy Guide calls Psych a "special part of the galaxy," but at the same time fails to notice that Diamondus, Tubelectric, and Medivo are planets, so I'm only so willing to trust it on that issue. Given that the JJ3 map shows that Carrotus is a significantly more varied environment than just palace gardens, I do like the neatness of putting everything in JJ2 (except for Flashback) on Carrotus.

Except that we do actually know what all the JJ1 planets look like from space, and only Diamondus remotely qualifies.