Did you pitch it as an 18-episode project? How did HBO react?
Danny McBride: I thought it would be a hard sell for them because obviously if the show worked you would think they’d want it to keep going. But they liked the approach of, “let’s give people a story that has a confident beginning, middle and end.” We’re not trying to drag out plot points and story points in the hope we can drag this out for season after season. This is one school year. The first nine [episodes] are fall term and the back nine are spring term. It gave an immediacy to the storytelling, you could set things up and pay things off without having to drag out the narrative.
Was the plan always to split it into two seasons?
DM: We followed the idea of a semester in a school. You’ve got two semesters and that seemed like a cool way to tell the story. It’ll make a little more sense once you’ve seen the whole thing but it is like two acts of the full story.
Source and more: Variety