Snape scowled at the mention of getting cut off, as if it had been an insult to his own control of Hogwarts. "In the event of an emergency, the staircases will behave themselves," he declared flatly, "I'll see to it. If it's not an emergency," he conceded, "it's better if I leave them to their own devices. The castle has its own..." he groped uncharacteristically for words, "...not quite a need for exercise, not quite nervous tics, but similar. If it doesn't work it off in relatively harmless ways like the staircases, eventually Peeves picks up enough of a charge to run riot."
"And are you seriously telling me that, while we are under siege, fighting for our lives, that trivia like a club must factor into our plans?" The sneer of glacial contempt that twisted Snape's gaunt face spoke eloquently of his opinion of that idea.