MechEngI think it's luck of the draw when it comes to the Miyota 8215 movement you receive. The tolerances don't seem to be quite as "tight" as, say, most Seiko movements, and I've heard and read of noticeable variance when it comes to finishing, accuracy, power reserve, etc.
Case in point, guessing by your comment, is that you're not getting close to the 40-hour power reserve as stated in the specs whereas the watch I received in this same drop pushes nearly 50 hours. I've tested it a couple times so I know it's not a fluke. Your mileage may vary, as they say. Cheers!