I have hundreds of dives with 3 man teams, and we have never, even once been separated (okay, once on scooters for about three mins). If you or your team mates are "often" lost, or "often" left behind :shocked2:, you are diving in a manner I am not accustom to, and without a doubt, more training would help you.Inman mentioned ... And the 3rd man in a 3-way often gets lost or left behind, in the real world.
Or maybe you don't speak from personal experience, but from what you read on the internet. But if it's personal experience, I want to give you hope, that is very possible and not difficult to learn to dive safely with a 3 man team.