Conversely
Producers find a new show idea that looks interesting and could be popular .....
Writers: yeah we got this idea that could be turned into an hour and a half hour long film ... it's very interesting, great plot dialogue, and there's a great twist
Producers, executives: Great idea! I love it! But it would give us more content if you could turn it into a series instead. Take the whole film and stretch it out across seven one hour episodes.
Writers: how?
Producers, executives: just cut it up into seven parts, slow everything down and make a dramatic cliff hanger at the end of every episode.