There isn’t a more rigidly formulaic television genre than the sitcom. Over a tightly telescoped span of 22 minutes, writers must introduce, escalate and resolve a situation, all while giving audiences the belly laughs that have hopefully made the show appointment viewing. They typically only have a week from table read to filming, which leaves the production some room for adjustments, but little in the way of experimentation. It’s all got to be on the page.

Even for a show like “Seinfeld,” where the cast maintained a high degree of spontaneity throughout each episode? Where Kramer’s (Michael Richards) abrupt entrances seem to throw off the entire gravity of Jerry’s (Jerry Seinfeld) apartment? Where Elaine’s (Julia Louis-Dreyfus) signature shoves feel like they come out of nowhere? Where the banter takes so many unpredictable twists and turns that the actors appear to be consistently off-guard?

If you’re not familiar with how sitcom production works, you might find it hard to believe that the remarkably talented fab four of “Seinfeld” didn’t improvise on occasion to keep things fresh or send a scene soaring over the top (like Kramer snatching the baby from the mohel in the Season 5 episode “The Bris”). Many years ago, Seinfeld himself was asked about improvisation in the sitcom that bore his name, and his answer might surprise you.

During a Reddit AMA in 2014, Seinfeld revealed that just about everything you saw over nine seasons of “Seinfeld” was scripted. According to the comedy legend:

“We improvised virtually nothing, as a matter of fact. That’s how good the actors were, that it sometimes seems like they are improvising. But we also knew each other so well that we knew exactly what sentences to put in their mouths that would seem natural. We just knew how they talked as people and as the characters, and that’s what’s really fun about the TV series is that you become an ecosystem where people feed on each other. The actors would inspire the writers and the writers would inspire the actors and it becomes a tropical depression.”

Television writers didn’t get nearly enough shine back in the 1990s (i.e. the pre-Peak Television era, when casual television fans discovered the existence of showrunners), but most “Seinfeld” fans are aware now of the phenomenal funny folks who summoned up such spectacular banter. You just couldn’t miss with a writing staff that, along with Seinfeld and Larry David, included people like Carol Leifer, Peter Mehlman, Alec Berg, Jeff Schaffer, and David Mandel.

This doesn’t mean the actors didn’t add their own flourishes. Kramer’s entrances became a go-to bit after Richards was late on a cue in the Season 1 episode “The Robbery,” while Elaine’s shoves were carried over to the series from Louis-Dreyfus’ penchant to push her guy friends upon hearing amazing or simply surprising news. The show’s writers also made last-minute adjustments on occasion, the most famous being the kiss-off line from Jerry’s coulda-been girlfriend Sidra (Teri Hatcher) in the Season 4 episode “The Implant.” According to Hatcher (as she told Vanity Fair in 2014), David fed her the line “They’re real, and they’re spectacular” right before the shoot. Obviously, everyone on “Seinfeld” was quick on their feet, but when it came to delivering the verbal goods, they almost always stuck to the script.