The story of the Gary Cooper classic High Noon starts some time between 10 and 10:30 am, and goes until around 12:30pm. So loosely, a 150-minute story reduced to an 85-minute run time, less than a 2:1 ratio.
At no time does High Noon pretend to be happening in real time, but the pressure of the clock is a continuous element in the story-telling. What other films can you name that operate in a similar fashion? Not just “the story takes place in one 24-hour period”, but one where the entire story takes place in that highly restricted time frame (but not in a 24-type “real time” manner). Let’s shoot for that 2:1 ratio as a benchmark.
Also, don’t count films like Sunset Blvd or Fight Club, where the beginning and ending of the films are separated by mere minutes, but the films are almost entirely told in flashback.
Phone Booth (2002) takes place in a fairly short period of time with the central character trapped in a phone booth, and can’t leave or a sniper will shoot him.
Except for the beginning, there’s My Dinner with Andre and the much superior Andy Kaufman film My Breakfast with Blassie costarring pro wrestler Freddie Blassie.
The entire movie wasn’t in real time, but I was impressed when, at the end of the original William Cameron Menzies juvenile sf film, Invaders from Mars, they set the time delay on the bomb for five minutes and, by golly, it takes five minutes of real time before the bomb goes off. I timed it.
I timed it partly because five minutes is a LOT longer than you think it should be, and they ended up padding that countdown with a lot of photomontages of scenes from earlier in the movie, and it seems to take forever.
there are undoubtedly other countdown scenes in movies where they really do take the amount of time that the timer says, but I don’t know of any.
Incidentally, director Fred Zinneman had a lot of clocks in High Noon to emphasize the passing if time. Many years laster, when he made Day of the Jackal, he did the same thing – only with calendars, to emphasize the countdown to the assassination. When I saw that film, it was clear to me qwhat he was doing, but hadn’t seen High Noon, so I didn’t realize how he was echoing his earlier film. (Day of the Jackal, of course, wasn’t in anything like “Real Time”)