I somewhat agree. It seems clear to me that its a consequence of not writing to a story arc, which in turn is a consequence of not knowing the running length o

I somewhat agree. It seems clear to me that its a consequence of not writing to a story arc, which in turn is a consequence of not knowing the running length of your story. Even the best execution I've seen are series that end ambiguously with open questions left for the audience to decide. In feature writing open endings are often considered edgy or avant garde, in series writing it is the most obvious of cliches. Series that have a known fixed length do much better imho. Mind you I think it is possible to execute on a story arc without knowing your running length in advance as long as you are within an order of magnitude in estimation. I just haven't noticed anyone trying.