Over a period of 60 years the number of episodes in a season of the average TV show ranged from 20-39 episodes per season.
I think it is less of a quality issues, and more of a serial vs procedural situation.
Most shows that have many episodes per season are more of procedural in nature, while many shows that have less episodes per season typically are serial. This isn't a rule, but more of a guideline, and there could be shows that break this, of course.
For a while in recent history, (Game of Thrones and many others) episodes dropped to 10 per season and now I’m seeing series dropped to 8 (Hanna) or even less.
Both GoT and Hanna are more of a serial show, where there is a main story arc over many episodes, seasons, or sometimes the whole show.
Procedural shows typically have each episode kind of story arc (The Twilight Zone, Friends, Law and Order, Scrubs), but sometimes there is a slight serial element where there is a main story arc across a half or whole season that each episode dedicates a small portion of time to, but there is usually a "monster of the week" that majority of the episode is about (Arrow, Supernatural, Buffy The Vampire Slayer, Fringe, Alias).
Blah! Now I am grateful that The Expanse is holding at 13 episodes.
This is more of a serial show.
If there are 8 episodes x 50 minutes, we end up with a glorified long movie or a movie and a sequel.
Typically serials are shorter, or have breaks within a season, because it is like a big, long movie, and sometimes (especially before binge watching) it is really hard to remember earlier episodes, characters, events...
One serial that had very long season, and really easy to forget the beginning of the season by the time you got to the end was the show 24.
Forgetting an episode of a procedural show typically wouldn't have as much of an impact as a serial because each episode has its own story arc that typically doesn't impact the main story arc, if there is one.
Now back to this, I originally said that it wasn't really about quality, but I am going to contradict myself a little.
I think that typically serial style shows tend to be better quality shows. I think they take more effort and time to write, direct, and produce serial show. Not to mention $$$.
I also think that the quality of TV shows are increasing and the amount of serial style shows are increasing.
While procedural shows may have been king over the past 60 years, I think this is changing, and TV is now being taken more seriously.
That is also why multi-camera and/or live audience shows/laugh tracks, something that used to be the norm, is now rare. This type of TV is poor quality, imo. I am glad to see more single camera shows being made.
en.wikipedia.org
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