The first stage of our trip to Italy took us to the Boston airport, along with two of our checked bags. The third bag, for no reason I could discover, came on a later flight.
It would be helpful if, in such situations, the airline would announce the point at which all of the baggage from a particular flight had been put on the carousel. That way I would know my bag was missing and could take action accordingly, instead of waiting around for another twenty or thirty minutes in case it was still coming. So far as I can recall, I have never observed an airline doing so.