American network shows historically ran to season lengths that look enormous next to modern streaming orders. The number was chosen to reach a resale market rather than to tell a story of a given length.
Reruns were where the money was
A network licence fee often failed to cover the cost of production, and studios accepted that gap because the real return came from selling the finished library afterwards.
Local stations buying reruns needed enough episodes to fill a daily slot for months without repeating too visibly, which set a practical minimum.
Reaching that library size became the objective of the first several seasons, and a show cancelled short of it was a straightforward loss.
Episodic structure made the library sellable
Stations aired reruns out of order, so episodes had to work individually, with characters reset by the closing credits and no accumulating plot to follow.
That is why procedurals and multi-camera comedies dominated the format for so long: they were the shapes that survived being shuffled.
Serialized shows are far harder to sell this way, which is a commercial fact that shaped decades of American storytelling.
Streaming changed the buyer without changing the logic
Services buying catalogue want volume too, because a long library keeps a subscriber inside the service for weeks rather than an evening.
The buyer is different and the incentive is the same, so an existing show with many episodes remains disproportionately valuable relative to its original cost.
This is why some of the most watched titles on streaming services are decades-old network shows that were made for a market nobody expected to survive.
Short orders shifted risk to the studio
An eight or ten episode order costs less and can be made with more control, but it never accumulates the library that made the older model profitable.
Streaming services frequently commission and own the show outright, which removes the resale market entirely and replaces it with an internal valuation.
Creators lose the long tail that syndication provided, and residual arrangements for streaming have been a central point of dispute in industry negotiations.
The threshold still appears in negotiations
Contracts and renewals often reference episode counts in ways that echo the older thresholds, even where no rerun market is being targeted.
Some producers deliberately push for enough episodes to make a library viable in case rights revert or the show is licensed onward later.
The number that once described a syndication requirement now functions as a rough measure of whether a show became an asset or stayed a project.