One specific situation that very regularly happens in Latin, which can affect students transitioning between schools, gifted students who are bored, upperclassmen who are only just starting Latin and are bored, etc., arises out of what is a fundamental misuse of one of the most commonly used textbooks, the Cambridge Latin Course.
The CLC was written for the needs of British students, who have a very different approach to Latin than American students. In Britain, Latin study is usually restricted to the top 20-30% of students academically (the British are much more comfortable with explicit ability tracking than we are, including in state schools), and begins in the equivalent of 5th grade. British students are also usually on a rotating schedule, and don't necessarily have a subject five days per week.
I think this fact explains a great deal about what happens when American schools try to use CLC but, for some reason, either don't really read the handbook/standards orientation documents or prefer to subvert them. The Cambridge red book (i.e. the story about Caecilius) doesn't have very much grammar in it because it's written for 5th graders who have many years to build Latin slowly, and in addition, stories that are popular and funny in 5th grade fall flat if they end up in 11th or 12th.
I'm very far from being anti-CLC (I hugely prefer it to Ecce Romani, for example, since eventually the stories do get far more engaging and complex than Ecce ever manages, and I think the "model sentences" remain a revolutionary idea), but I do get really frustrated with the trend of using just the red book to comprise a high school level Latin 1, when the CSCP makes it pretty clear that a high school Latin 1 that meets the standards of an average US state needs to go on to the blue book as well (ideally finish it). Using red in 7th grade and blue in 8th, which is common at independent schools, works out just fine, but any school that keeps 9th graders or above in the red book all year really isn't teaching them enough Latin to add up to any real benefit when they finish the language. I strongly believe that the goal of high school foreign language education should be proficiency; a high schooler who wraps up foreign language at the end of Latin 2 somewhere in the CLC blue book is not proficient by any meaningful definition.
And I feel very sorry for the plight of students who move/transfer after a Latin 1 that was really a Latin 0.5, and have an incredibly tough time with their new class, the National Latin Exam, or just about anything else Latin-related.