“Percy's been acting very oddly this summer,” said George, frowning. “And he has been sending a lot of letters and spending a load of time shut up in his room… I mean, there's only so many times you can polish a prefect badge… You're driving too far west, Fred,” he added, pointing at a compass on the dashboard. Fred twiddled the steering wheel.
The thing I don't quite understand from that sentence:
What does "only so many times" convey exactly? Is it saying Percy didn't get many chances to polish a prefect badge?
-- Excerpted from Harry Potter.