When several of us were in CVG at the Delta tower, we saw a lot that goes on. And answer is that it all depends on the circumstances. They have a wealth of information available to them to make their decisions but it's all a balancing act. We learned that sometimes gate changes are made to accommodate connecting passengers. It might not be a coincidence that you were running late and it just happened that your connecting gate was right beside your arrival gate. It's gets complicated when only certain planes can go to certain gates, etc. Your best chance for a hold for a connecting flight: be making the same connection that a unaccompanied minor is.