In what way? If we're discussing exclusively the aspect of healing, then they gain nothing from leaving people injured. [Granted, she's not sure how he'd explain away the injuries and there's always the risk that would lead to some kind of problem. But then, she highly doubts the fight club is as secret as it's claimed to be, either.]

Though I'd consider they might slip you some of that tea they're so desperate to push on us for this little celebration of theirs, if they had the opportunity.