Posted by Denny:
"Some racers believe that opening up the 2nd end gap even more (say an additional 10%) can improve overall ring sealing by allowing trapped gases to escape before they blow past the top ring and cause ring flutter at high rpm (say above 5000 to 6000 rpm)."

What's alluded to here is that the rings seal on the bottom of the ring against the flat shelf of the ring land. Blow-by past the cylinder wall/ring face junction of the top ring can cause a pressure build-up between the first and second ring and can apply enough pressure to unseat the top ring off the ring land and eliminate the seal. By allowing a little extra room for these gases to exit past the second ring and into the crankcase, the integrity of the top ring seal at the ring land is assured.