Let’s talk cartoons. Shitty cartoons.
You know the ones. Where the heroes fight off bad guy after bad guy. Series featuring actual monsters as notorious for this. Think Pokemon, Digimon, those kinds of things. The ones where they shout out the names of their moves. Every episode, they’ll have a new threat to deal with. They engage it, struggle against it, and ultimately defeat it. Next episode, exactly the same deal, with a different monster (and sometimes setting). Made plot relevant by mentioning elements from the overhanging arc. “Yeah we have to beat up that guy because he used to work for Villain X, and X is our nemesis!”
And I find it absolutely disgusting. It really shits up the series for me as soon as I notice this pattern. I just find it so cheap, an easy way to churn out episodes and show off silly character designs (or monsters, of course) while they’re at it. It adds nothing of value to the series as a whole. It’s just filler!
It doesn’t have to be bad, per se. You can throw in some nice stuff like character development, obscure backstory references, etc. Hell, the monster/enemy can even be tied in to a much bigger story arc. But as I said, this usually happens in a “oh yeah this happens to be relevant, deal with it” manner, rather than actually being integrated in and significant to the plot.
But hey, what do I know about story writing for series.