Every free moment that Hermione had was spent practicing what Aberforth taught her two days before. She wasn't foolish enough to try to cast actual spells yet on her own inside her tent, but she could at least practice the fundamentals of the meditation and incantations required. It wasn't enough that she was successful because her latest teacher provoked a strong emotional response. She had to get proficient enough to perform on a whim. Seconds mattered. She couldn't afford to dredge up thoughts of her son every time she needed to cloak her magic.