If you are not a seasoned traveler with good elite status don't do it. If you like the adventure and can adjust to the risk of being stranded somewhere, have fun. I have an upcoming mileage run with a 8 hour layover involving transit from nrt-hnd. A missed connection would be highly inconvenient and involve a last minute mileage award. Luckily, I have sufficient miles in multiple alliances to allow for this risk. If you are not comfortable with a potential delay or high cost last minute ticket, avoid these issues by booking as a single pnr.