The disparity between the Legends and Flash writing room is amazing.
With Legends, they seem to build on things. Beebo is organically introduced over the course of a season for a big payoff at the end. A weird offhand joke like Gary's nipple being bit off becomes an important plot point later on. The Fairy Godmother comes back as a callback joke, and then as another important plot point. They also seem more willing (and able) to re-adjust on the fly - Biff was originally supposed to be full-on evil, until they found that wasn't working at all with the stuff they'd already done, and the actor, so they pivoted, and now we get the awesome theme park nonsense.
With Flash, it's the complete opposite. Stuff just happens, and in most cases everyone immediately forgets it. Stuff that seems like it will be going somewhere, like "this house is bitching", never goes anywhere satisfying. Half the characters that are introduced just abruptly wander off, never to be seen again. The show frequently wanders down plot cul-de-sacs. The writers just don't seem to have an understanding of how the show is progressing, or how it's being received.
It's mind-boggling that a show with way more characters that spans the entirety of time has much better characterization and a far more natural overall story arc progression than a show about basically six people who hang out in a concrete basement.