A number of years ago, I went to the movies a lot, to the point that it was hard to find a movie on the marquee that I hadn't seen. In that time, I became painfully aware that the first 20 minutes of (almost) every movie is exactly the same: introducing the character(s) to show his or her typical day so that we know what happens in the movie is *not* typical. One common example of this includes showing a family that is WAY too happy; nothing in this family has every gone wrong, and everyone gets along perfectly. It would be a REAL SHAME if something were to happy to that perfect family. It's so extreme that it's obvious something terrible is about to happen. I guess in modern parlance, this would be called a "trope". This repetitive 20 minute section, although different, makes me think of The Wadsworth Constant.
This is less pronounced in TV series and movie sequels. In TV shows, the first episode is the same as those first 20 minutes of a movie, but, once you're past that episode, you never have to deal with it again. In movie sequels, the first installment spends the time introducing the main character, which is why the second movie in a trilogy is the most well-liked: it can actually just get to the real story. There may still be some time dedicated to introducing the new antagonist at the beginning of sequels though.
What repetitive part of movie formulae gets on your nerves?
