Well there are two issues there, one is the time, the other is the principle.
I'm more interested in the principle than the actual time, the British record for the time to fly 100 circuits I think worked out at 40 seconds a go! So, let's say 4 minutes, whatever.
I timed a typical circuit today at five and a half minutes from touchdown to touchdown, so probably 5 minutes from t/o to touchdown. That's a 1500 ft twin circuit at Cambridge. I think I'd have trouble shaving a full minute off that, but could live with 4.5 mins.
Of course I didn't time the "No 2 to the Gulfstream V, caution wake vortex recommended spacing is 6 miles" one.
