In book 1, Harry, Hermione, Ron, and Neville altogether got 160 house points from Dumbledore at the end of year, for defeating Voldemort/Quirrel and for Neville, standing up to his friends. But before that (still in the first book) Harry, Hermione, and Neville were caught sneaking out at night by Mcgonagall (Harry and Hermione were there to set Norbert free and Neville to warn them about Malfoy) and Mcgonagall took away 150 house points (50 each) from Gryffindor. SORRY WHAT- DEFEATING VOLDEMORT AT THE AGE OF ELEVEN GOT 160 POINTS AND SNEAKING OUT TOOK OFF 150-
I think Mcgonagall's just really strict, but you get my point.