When Natasha Lyonne, Leslye Headland and Amy Poehler put their heads together to come up with a show unlike any other, they knew they wanted it to be both funny and unafraid to tackle traumatic experiences that most comedies would avoid at all costs. “We were always interested in themes that weren’t necessarily comedic on the surface, though we figured given our backgrounds that it would be pretty f–king funny,” says Headland. “So we knew going in that we were going to be straddling that genre line.”

The result was “Russian Doll,” a series that strategically rejects labels (and drops its eight-episode first season Feb. 1 on Netflix). It’s a twisty feat, layering jokes on top of tragedy on top of jokes to tell a complex story about a woman trapped in a time loop — and each installment only needs 25 to 30 minutes to do it.

“I remember saying that we should think of it less as a comedy and more as just a 30-minute show,” says Headland. “To industry standards that means a comedy, but to us it doesn’t have to mean that.”

Conventional TV wisdom goes that dramas run at least an hour, while comedies run 30 minutes or less; even the Emmys now require shows to petition an Academy panel to justify why they should be considered in a genre that their run time suggests they don’t belong to. But increasingly, distinguishing series’ genre strictly by virtue of their length has become a far less accurate way of assessing them. While the TV landscape is vast and ever-expanding, some of the most compelling shows are evolving the medium from within the half-hour space, blending tones and subverting expectations.

Take “Homecoming.” After gaining attention and accolades with his USA drama “Mr. Robot,” Sam Esmail was excited to adapt Gimlet Media’s dark audio drama podcast “Homecoming” into a TV series, and ended up pushing back against tradition and choosing a half-hour run time. “Everyone went on autopilot assuming we were going to adapt it into an hourlong drama,” Esmail says. “And I remember having this moment, just pausing to question that.”

Bleak though “Homecoming” may be, Eli Horowitz and Micah Bloomberg’s podcast told its story — about a therapist who helps soldiers transition to civilian life — in 30-minute episodes, and Esmail didn’t see a need to change the length when translating it to the screen just to check off the “drama” box. Defaulting to that definition “felt kind of archaic,” he says, when perfectly good half-hour chapters were waiting in the wings. “Keeping the episodes more compact,” Esmail decided, “might feel more impactful than dragging them out to an hour.”

That calculated gamble paid off. When Amazon dropped 10 half-hour episodes of “Homecoming” in November, the series immediately made an impression, earning critical acclaim and several Golden Globe nominations for its trouble. (And yes, those nominations were in the drama categories.)

Esmail has one more season of “Mr. Robot” to wrap, but he’s excited to explore how the shorter format can work for him in future, precedent be damned. “I gotta be honest: I’m obsessed with this new format,” he says. “I probably will tell everyone in earshot that I’m only doing half-hour dramas from now on.”

What makes the 30-minute drama structure so appealing for top showrunners? For starters, it removes some of the pressure that comes with having to juggle several narratives, says Tanya Saracho, creator of Starz’s “Vida,” which focuses on estranged Mexican-American sisters who return to their East L.A. roots. “In the one-hour shows I’ve been on [‘Devious Maids’ and ‘How to Get Away With Murder’ among them], you have to serve so many storylines,” she says. “If ‘Vida’ was a longer show, I think I’d have to serve plots first. But this way, I get to follow my characters’ psyches and their emotional lives. Sometimes when the episode ends, it doesn’t even end with plot but how the characters are feeling.”

The ability to slow down the action and zero in on character motivations is what ultimately led Esmail to use a shorter format for “Homecoming.”

“I’m sure there was this instinct to make it more dramatic, to add more set-pieces and pyrotechnics,” he says. “I really resisted that, because I admired the spirit and the intimacy that the podcast had. But I [also] think something that was this slow of a burn could only work in a half-hour. I don’t think the audience would have had the patience [otherwise].”

Kit Steinkellner launched her half-hour drama “Sorry for Your Loss,” about a woman dealing with the sudden death of her husband, on Facebook Watch last year. She agrees, as both a TV writer and a viewer, that a shorter run time of tighter material helps keep an audience engaged. “There are shows where scenes feel unnecessary and everybody’s tap-dancing a little bit,” she says. “I don’t like my time being wasted, and I don’t want to waste anyone’s time.” Not having to slog through hour upon hour of often heavy storytelling is a welcome surprise at a time when the TV industry is embracing a near-frantic “More is more” mind-set.

Not that the half-hour drama or even “dramedy” is a brand-new concept. Some of TV’s earliest dramas — from “The Twilight Zone” to “Gunsmoke” — began as half-hours until the medium settled into a more strict genre binary and used run time to enforce it. More recently, Showtime briefly cornered the market in pitch-black, acidic half-hours with genre-busting shows like “Weeds,” “Nurse Jackie” and “United States of Tara.”

Indeed, the new wave of half-hour creators is quick to point out several examples that were influential. Esmail steered “Homecoming” by studying HBO’s 2008 therapist drama “In Treatment.” Headland recalls marathoning Starz’s silken thriller “The Girlfriend Experience” and referring back to it when she, Lyonne and Poehler were fine-tuning the tone of “Russian Doll.” Steinkellner praises HBO’s “Girls” and Amazon’s “Transparent” as shows that prove that dramas don’t need to push 60 minutes to deliver emotional gut punches. Saracho cut her TV teeth on HBO’s “Looking,” an intimate and contemplative character drama about a group of gay friends in San Francisco.

For all these shows’ wildly varied subject matter and execution, they share one crucial trait: None of them needs to worry about commercials. It’s not impossible for a half-hour show to play against genre while factoring in hard act breaks (FX’s “Atlanta” springs to mind), but by all accounts, ad-free sure does help. Shifts in the television marketplace toward subscription streaming models (see Netflix, Amazon and soon Disney Plus) have created more demand for programs that don’t adhere to traditional storytelling methods designed for ad-supported linear networks.

Robin Schwartz — head of the TV division for Big Beach, which produces “Vida” and “Sorry for Your Loss” — believes premium cable and streaming platforms are particularly good fits for the kinds of character studies that just don’t work within traditional TV business models. “I think it’s a much harder sell for platforms and buyers to hear ‘a character drama without a big story engine’ and think that it could sustain itself in the hour format,” she says. “And if you think about ‘Sex and the City’ or any of those half-hour cable shows, you can tell a story. What it’s almost impossible to do is tell a great story in 20 minutes. Doing a half-hour drama with commercials on network would feel impossible.”

That’s why some creators are starting to develop shows with ad-free streaming networks in mind. “It was never considered to be a television show that was going to have ads or be seen week to week,” Headland says of “Russian Doll.” Instead, the co-creators concentrated on making a show that would inspire an audience to marathon it. And they didn’t have to explain whether “Russian Doll” was a comedy or a drama. “If anything, Netflix was pushing for the show to be more itself — the more individualistic and unique, the better,” Headland says.

Headland reasons that Netflix’s encouragement to be singular is mutually advantageous. It’s in the creators’ and the company’s best interests to have a series that stands out by flying in the face of what we’ve come to expect from TV. If done well, that’s the kind of breakout that streaming services like Netflix can tout as successes unique to their platform. And it gives writers the creative freedom to try something unexpected without having to paint by the usual numbers.

Still, it will take some work for everyone to catch up to the idea that run time shouldn’t dictate subject matter. Shifting norms isn’t as easy as expressing the desire to do so.

“Right now the industry is so stuck in ‘either/or’ land, but viewers are not listening to that. They’re just gleefully consuming stuff,” says Saracho. “We should either stop defining or redefine.”