For any writer, it's important to match the length of what one is writing to the strength and scale of the story. Some ideas are essentially suited to a short story, others need a full-length novel to do them justice. I can think of one or two of my short stories that I might conceivably have extended into a novel, but very few. And I'd certainly like to think that none of my novels are really just glorified short stories. On balance, I believe it's much better to "waste" an idea by turning it into "just" a short story rather than risk boring a reader by stretching it out too far. But then, I am a lover of short stories...
I can think of one or two novels at least that seemed a bit over-extended. A Taste of Honey, a rather odd book by Gerald Heard, is one that springs to mind. It's a book with Sherlockian echoes, which I read a long time ago. It does have admirers, but I'm afraid it didn't do much for me. Julian Symons was right to describe it as a curiosity.
The problem of length seems to arise more often, though, with films. I've watched quite a few that seem to outstay their welcome. And that is the case with a fairly recent movie, The Ministers, which stars Harvey Keitel as a veteran cop with a dark secret, and John Leguizamo who plays two brothers, one of them scarred both physically and mentally. A pair of hooded killers are on a mission to kill - but why? There seems to be a religious aspect to the mystery, but frankly, very little is made of this in the end.
There are some good aspects to this film, not least the acting of Leguizamo and, in a minor role, Wanda de Jesus, but even though it is only 90 minutes long, it drags. The problem is that there just isn't enough meat in the story (or, perhaps, the writer failed to make the most of what meat there was.) A classic example of a storyline that simply did not justify the time it took to watch the film.