A season of television used to run to twenty or more episodes and now often stops at six or eight. The reasons are largely economic and structural rather than creative.
Advertising once dictated the length
Broadcast schedules needed a programme in a slot every week for most of the year, and advertising revenue was collected per episode aired across that long run.
That model rewarded volume directly. More episodes meant more inventory to sell, and the season length followed the shape of the broadcast year rather than the story.
Subscription services collect the same monthly fee regardless of how many episodes a show produces, which removes the incentive that made long seasons worth making.
Per-episode cost rose sharply
Production values expected of a drama today are closer to those of a feature film, with location shooting, extensive effects work and longer schedules per hour.
At that cost, twenty episodes would be unaffordable for most productions, so the budget buys fewer hours made to a higher standard.
The trade is visible on screen, and it is the main reason a short season can feel more substantial than a long one from an earlier era.
Casting depends on shorter commitments
Film actors will commit to a few months of work but not to the near-continuous schedule that a long season demands across most of a year.
Short orders opened television to performers who would previously have declined, and the resulting talent shift became self-reinforcing across the industry.
It also changed how writers construct roles, since a character can now be built around an actor available for a defined and limited window.
Release patterns changed the shape of a season
Where a season is released at once, the episode boundary stops functioning as a week-long pause and becomes closer to a chapter break.
Writers no longer need a hook every week to hold an audience across a gap, which removes much of what padded older seasons out.
The story is instead built as a single long arc, and that arc rarely needs twenty hours to complete without repeating itself.
Short orders shift the risk profile
Commissioning six episodes limits exposure if a show fails to connect, and it allows a service to launch more distinct titles from the same annual budget.
The cost is that a series has less room to find its footing, and shows that once improved in a second half now get judged on their first two hours.
That pressure explains why openers have become so front-loaded, carrying a weight of exposition and incident that older pilots could spread out comfortably.