From the OA and UnReal to Who is America?, dropping shows into the world with little or no promotion is the latest TV trend. Is it just gimmickry and do viewers lose out?

The debut of a TV series has traditionally been the last of many phases in the show’s publicity drive. First there’s the commissioning announcement, the casting news, the pieces reporting that shooting has started, the YouTube video or tweet confirming the date and the print previews in the final run-up. By the time the thing is actually on, you’d be forgiven for lacking the energy to watch.

But on Monday night on Channel 4, Sacha Baron Cohen’s new prankfest Who is America? began, just a week after we learned of its existence. Reprising the 20-year-old Brass Eye format of duping public figures with ludicrous political campaigns might not be exciting, but the surprise scheduling was.

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The following day, US fans of the drama UnReal who didn’t know when season four would air suddenly got their answer when the entire thing appeared on Hulu. (It arrived in the UK on Tuesday on Amazon Prime.) Television is some way behind music when it comes to surprise drops – Beyoncé, David Bowie and Childish Gambino have all, in recent years, benefited from PR campaigns that consist entirely of “New thing. Click here. OK bye” – but with the number of competing shows seemingly expanding towards infinity, the no-warning release could be a big part of TV’s future.

Logistics most likely pushed Baron Cohen towards a last-minute PR strategy: deceptive undercover series clearly can’t be announced prior to filming, and even with the footage in the can, an early trail would merely give disgruntled victims’ lawyers time to try to halt the broadcast. UnReal’s sudden return, meanwhile, was evidence of a show in its death throes: a delay in showing season three, and a shorter run of episodes in season four, meant there was already another season finished when season three was shown – and it had been decided that the new one would be the last. If you’re cancelling a show, you might as well burn it off and get one last hit of column inches as you do it.

Both, however, succeeded in making their brief flash in a crowded sky a little brighter, by getting people talking: because in the chaos of 2018, the No 1 way to make your show a success is old-fashioned word of mouth. That’s the only way for Netflix, which doesn’t care whether you watch its new shows on the day of release or not, and has too many of them to do proper pre-publicity anyway – so it relies on word-spreading. An effective way to start that is for viewers to say to their friends/followers: “I didn’t know this was on Netflix! Did you?”

Apart from The Crown, which operates by its own rules and had a colossal PR campaign to go with its luxury budget, all Netflix’s biggest shows are sleeper hits: Stranger Things emerged during the summer of 2016 and took a week or so to take off, while Making a Murderer dropped right before Christmas and didn’t attract any foaming thinkpieces until the New Year. Kooky sci-fi The OA also debuted in December, and was only announced four days in advance. Netflix has done a full Beyoncé by dropping a film, The Cloverfield Paradox, with no warning whatsoever, and it’s surely only a matter of time before it goes one better than it did with Chris Rock’s stand-up comeback Tamborine – announced the day before it arrived in February this year – and releases a whole TV series it has never previously mentioned.

Facebook Twitter Pinterest Slow burn … Stranger Things. Photograph: Netflix/Kobal/Rex/Shutterstock

Netflix has the advantage, however, of making more impact by dumping an entire series in one hit: the social media posts about a show’s existence intensify as people share their reaction to more and more episodes. That’s a step the networks showing Who is America? – it’s on Showtime in the US – didn’t deem it advantageous to take, but it is increasingly what viewers expect.

The BBC is also still tied to showing most of its programmes at a particular time on a prearranged day. That doesn’t make it completely inflexible: BBC Three’s online-only status means it can drop whole seasons at once, and even BBC One is now taking a cue from Sky Atlantic and routinely releasing whole box sets on-demand as soon as episode one has aired. Hard Sun, Civilisations, Motherland and The City and the City have all premiered in full on iPlayer in the past 12 months and, while none of those shows were landmarks in terms of how BBC content is consumed, there’s a major opportunity coming up.

If the new, eleventh season of Doctor Who were to be available as an iPlayer binge – there’s been some industry speculation that it could – it would signal that the game has truly changed. How can they get that buzz to full fever pitch? Easy. Just don’t warn us beforehand.