No, see, if two days pass and we haven't gotten a wolf yet, the shepherd will give a warning. That's how we can know if we get a wolf if we focus on only the first group: if there's no warning, we know we got the wolf, and if there is a warning we know the last person is a wolf.

I'm not completely sure, but I think Cesare and Ash might be good people to talk to. They seem to know what they're doing.