Revealing mistake: After the dance, during the Mercedes vs. Jaguar "race" back to the diner, much of the entire scene takes place at the same intersection of Victory Blvd and Olive Ave, filmed from different angles. Note the Jiffy Lube and Enterprise (cars) on the corners, which are actually across the street from one another. (00:47:25)
Revealing mistake: In the beginning of the dance scene, when Sam gives Carter her phone so he can set the alarm, the phone isn't even on when he is programming it.
Answer: Yes, this happens in most schools. The reason is that students are more likely to pay attention to announcements that are not made by a boring school employee. In many American schools, we have a phenomenon known as "home room". This is a short period usually first thing in the morning that is non-instructional when announcements are made, forms are filled out, and administrivial functions that don't have anything to do with any one class. At schools that don't have this, they have a thing called "study hall" or "independent study" which is a period where you sit in a classroom and work on your assignments, special functions for the school admin. like you are talking about are frequently done at these periods by students who are "working in the office" rather than studying. Then, there are schools that actually have classes in journalism, broadcasting, etc. where this activity would be part of the schoolwork.
Myridon