It's not just that they might get cancelled either, it's the way they all end up being written often without knowing they'll be extended to another series. The result is storylines that lead up to dramatic conclusions and then suddenly they're finding excuses to drag out previously unimportant elements or crowbar in new characters and it goes to shit and then they get cancelled.
Still, it's worth watching some so long as you can not care too much, or it might be that you're talking about Better Call Saul or The Expanse or something and it'd be a shame to miss out on those.
