Flip or open turns in distance races?

In the Olympics everyone does flip turns in the 1500m but I was wondering whether many ordinary mortals resort to open turn for longer distances in the pool? I think I am quicker flipping in a short distance race but it feels as though as I am going slightly into oxygen debt, so I'm not sure they're beneficial over long distances. (I am experimenting but I don't do enough long distance races to have much data.)