"Good," he answered. He'd continue to do both then, whether she fell asleep or not. Even if he had to leave before that point, she'd be relaxed enough to get a couple hours in. Of course, she could do that now.
Ron didn't know that he could go until lunch without knowing that she'd at least had a nap, and preferably several hours of sleep, considering what they'd be up against that night, advantage or not.