If any sitcom could work without a script, it's Peter Kay's Car Share.
Over two series, the seemingly natural in-car chemistry between Kay's John Redmond and Sian Gibson's Kayleigh Kitson was its main selling point. To the extent that it did feel like you were just eavesdropping on two friends on the way home from work.
But ask anyone who's worked in TV comedy and they'll tell you just how important a well-crafted script is to a show's success. It's more than a jumping-off point, it's the blueprint.
To forego this and rely solely on the cast's improv skills is quite a gamble. And in the penultimate episode of Car Share (the finale is broadcast later this month), it just about pays off.
Kay, who was forced to cancel his huge stand-up tour earlier this year, makes something of a comeback appearance to introduce this episode: "We've done something a bit different... we wanted to see what would happen if we filmed a whole journey without a script."
And soon we're in familiar Car Share territory, with the Forever FM soundtrack providing the cues for much of the easy, relatable comedy of everyday life.
A misjudged opening skit about what to do in the event of a stroke on the back of hearing Edwyn Collins's 'A Girl Like You' probably should have been left on the cutting room floor, but Kayleigh's observation that fried egg and Chicken Kiev should never share a plate is more like it.
There follows more amusing misheard lyrics, M People singing impressions and John's utter disgust that Kayleigh has never seen a James Bond film.
"Get out. Now," he jokes.
Even a seemingly real traffic accident they drive past sparks an amusing anecdote from Kay/John.
If anything, Gibson seems more comfortable with this improvisational approach. By contrast, you can almost see Kay's comedic brain ticking over as he listens to her ad libbing, prepping his response. But that's hardly a major criticism: many of us probably do this in real life too, after all.
The two actors do earn a mid-episode break during a lengthy agony aunt segment on the radio where all they have to do is react with increasingly dumbfounded facial expressions - although the story itself feels dated in mining a tale of a cross-dressing husband for comic effect.
Car Share would falter if all it consisted of was this light-hearted joshing. The drama is in the not-quite-relationship between John and Kayleigh, and eventually the conversation does take a more serious turn.
When John muses that "happiness doesn't last" citing his disappointment with the ending to A Christmas Carol, Kayleigh replies: "Everyone has a little whinge but the difference is, that film has clearly taught you nothing."
The tension is between his natural cynicism and her glass-half-full outlook, and she's clearly irked.
A chat about teenage romance ("When I were 13 I'd have done it upside the skip," John says) leads inevitably to another case of will-they-won't-they, and it's Kayleigh who presses the matter.
"All I want is a cuddle on a Sunday night with a Chinese... We can have it at yours.. well I'm not going to turn up uninvited."
And so they make a date. "But I'm not watching Bond," she adds.
Whether or not a happy ending awaits in the final episode, this was a game attempt at an entirely unscripted half-hour of comedy.
But it also underlined how a good script can work wonders.
The final episode of Peter Kay's Car Share is on BBC One on Monday 28 May. You can catch up with Unscripted on the iPlayer