A lot of Nancy Drew books have annoying finale chapters, which take place a week later. Is there a TV Trope category for this? Because there should be.
Here's the pattern. In the penultimate chapter, Nancy has a big showdown with the culprit. She "defeats" the culprit, whether that means running away, stalling until the police arrive, or physically attacking the culprit. The finale chapter takes place a week later, when the mystery is over and done with. Nancy is usually talking to her friends, and she casually ties up one or two loose plot ends. The end.
The "finale chapter which takes place a week after" annoys me, because, by its very nature, it's totally removed from the main story. By skipping ahead a week, you just skipped over anything and everything that could be of interest to the reader.
Say the mystery was about a sports competition. In the finale chapter, we're told what the result of the competition was. No, we don't get to see the competition ourselves. We get told about it, second-hand. Even if the competition was important enough to be the focus of the entire book, it wasn't important enough to actually be IN the book.
I think all of the Nancy Drew games do this; Nancy stops the culprit, and you get told what happened a week later. The games usually handle this pretty well, but I could totally understand if, for example, some players were upset that they never got to see the play in Labyrinth of Lies.
I mention this, because I just finished reading Gold Medal Murder, which is Nancy Drew Hardy Boys Supermystery 4. The finale chapter was awful. It was as short as possible, almost like the author wrote it, only because they had to. It skipped over the big event--the victims winning the Olympics--and it didn't even try to explain any the loose plot ends. These loose plot ends include the culprit's motive, in multiple instances. It really made me upset.