"Either?" Dean was watching him closely, not so good at reading Sam these days that he could necessarily predict whether that was a warning or Sam being kind of a snot. It could have been either. "This is my life, Sam. I don't want to be trying something every other week. We can't be throwing any magic we get our hands on at the damn thing. A few more duds and it'll kill me way faster than I want it to."
Even then, he wasn't as forceful with that as he thought he'd be. It probably sounded like he was just tired, or didn't want this to become Sam's new obsession, but there was a part of him that wondered if it wasn't better to speed up this whole process.