To add to that: Weisman and Vietti were supposed to have been working on the GL show before making YJ. It was supposed to be YJ's premise (black-ops team of younger recruits) but with the GLs, with Hal and the other Earth Lanterns, as well as Kilowog, as recurring menotors. The main trio would've been Charlie Vicker, Arisia, and Arkkis Chummuck.
Weisman and Vietti were moved to Space Ghost after the GL movie was pushed back and Timm, Volpe, and others made GL:TAS. Space Ghost fell through and Weisman and Vietti made YJ.