Television writing was traditionally done alongside filming, by a room that stayed together through a season. A shorter arrangement, assembled before a series is commissioned, has become common and has consequences beyond scheduling.
The traditional room overlapped production
A staffed room worked while episodes were being shot, so scripts could be adjusted according to what was actually being produced.
If a location proved unusable or a performer brought something unexpected to a character, later episodes could respond within weeks.
The room also generated a continuous relationship between the writing and the practical constraints of making the thing.
A mini room front-loads the work
In the compressed arrangement, a small group is hired for a limited period to develop scripts before the series is approved.
If it is not approved, the writers are paid for that period and the project ends, which is a considerably cheaper failure than staffing a full season.
If it is approved, the room has frequently already dispersed, and the writers have taken other work by the time production begins.
Scripts arrive without production feedback
Material written before anything has been shot cannot account for what the production discovers, since none of it has happened.
Problems that a room would have caught in week three surface on set instead, where solving them is far more expensive.
Showrunners then rewrite alone during production, which concentrates an enormous workload in one person at the busiest possible time.
The training path was the real casualty
Writers historically learned production by being on set, watching their scripts be made and understanding why a scene did not work.
That experience is how a staff writer eventually becomes capable of running a show, and it cannot be acquired from a room that ends before filming.
The industry consequence is a shortage of writers ready to run productions, arriving several years after the practice became widespread.
Why it persists despite the objections
The arrangement defers cost, and deferring cost is attractive to any organisation approving many projects that will not proceed.
It also fits a commissioning process in which far more series are developed than are ever made.
The saving is real and it is measured in the development budget, while the costs appear in production overruns and in a workforce that has not been trained, which are recorded elsewhere.