Oh Yeah! was really more of a vast number of pilot episodes for Nick under the guise of a series. There were almost 100 segments comprising over 30 half hours, probably 60 of them ended up as one-offs, the others like Fairly Oddparents and Chalkzone were sometimes 4 or 5 segments. Because of the very diverse nature of the shows themselves, the series is often jarring and confused, but understand the real goal of the show was to generate new series. Chalkzone and FOP were the greatest successes (the Invader Zim pilot was aired as part of Oh Yeah! but had been completed before). There are a few diamonds in the rough, but you often need patience to find them. As others have pointed out, Cartoon Network was the first to try this method with Dexter's Lab, Johnny Bravo and Powerpuff Girls being amongst the shows that evolved from shorts.