>>149949370
How? Most American cartoons are either original IPs or sequels to cartoons that were original IP, they don't need filler because there is nothing to adapt. On the rare occasion in which the cartoon does have source material to work with, they rarely ever take it seriously enough to adapt the storylines accurately or even recognisably, leading to something that might as well be made up from scratch. The average Marvel or DC adaptation seem like they only resemble the source material conceptually, and even they I suspect that's more often than not a coincidence because it's hard to imagine that a comic book like Batman, which has lasted almost 90 years by now and has had countless side-books, hasn't pretty much done every story concept several times by now. The only currently ongoing cartoon I know of that likely has some actual filler is Invincible, and in that case it's likely because they need to fill each episode rather than stay behind the source material which ended around the time the show started production.