Ideally the famous Korean Street Food has 6 wedges in each bun which means it is sliced 3 times. And personally I believe the buns also look good when cut into 6 wedges and not 8 wedges. It is a personal choice though. The main point to remember is that you are keeping the base intact and not slicing it throughout irrespective of whether you are slicing it 3 times or 4 times.