In my experience most TV shows turn to crap by the 3rd season. A few exceptions by really talented people; but most people working on second-rate shows don’t have or aren’t allowed the creative vision to plot out a 5 or 6 season story arc. As you said they turn into melodrama.
I enjoyed The Expanse through the end of the third season. It was an excellent ending. Now it’s like a bad sequel.
I think they are steeped in “make it up as it goes along” mode.
Mr Robot tied everything together awesomely in the final episode of the final season. So did Monk. And Psych, for that matter.