As intelligent and responsible as Hermione is, it's difficult to remember that she's just a thirteen year old girl in the Prisoner of Azkaban. Not a lot of young students can take on that amount of pressure, workload and of course, time travel. It's good that Dumbledore trusted Hermione with the Time Turner but why was it only used to save Buckbeak and not Harry's parents, or used to stop Voldemort's birth in the first place? And why does she only have it for one year? It's not as though third year is the most important in terms of her studies and the curriculum at Hogwarts.
