I have the Kuryakan gas cap so I can't really speak to the regular filler cap but I put the nozzle into the tank about 1/2" and let the auto shutoff stop it for me. No overruns so far and generally the same amount of fuel based on my trip meter.

A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort. Herm Albright (1876 - 1944)