In Harry Potter and the Prisoner of Azkaban, Hermione turns the time Turner 3 times to take herself and Harry 3 hours back in the past. When they do so its 11:55 so that means they go back to 8:55. This takes them to the time when Buckbeak is about to be executed. But the execution is supposed to happen at sunset (which I assume can't be later than 7). So how are they there at 7 when they only went back 3 hours from 11:55?
From the chapter 16, "Professor Trelawney's Prediction":
"It's from Hagrid', said Harry, ripping the note open. "Buckbeak's appea - it's set for the sixth."
"That;s the day we finish our exams," said Hermoine, still looking everywhere for her Arithmancy book.
Also from the same chapter just after Trelawney makes her prediction:
"Buckbeak lost", said Ron weakly. "Hagrid's just sent this."
Hagrid's note was dry this tim, no tears had splattered it, yet his hand seemed to have shaken so much as he wrote that it was hardly legible
Lost appeal. They're going to execute at sunset. Nothing you can do. Don't come down. I don't want you to see it.