Game shape is a wacky thing. I had one player drop from 9 to 8 playing 62 minutes, and then rise from 8 back to 9 playing 87 minutes. I've been tracking my game shape shifts with different minute thresholds for the last ten weeks, and basically the main thing I've discovered is that if you keep your weekly minutes in the target range (48 to 72 minutes) you'll be 7 or above in GS. I've never seen a 7 drop to a 6 when you land in the target range, but you are not guaranteed to rise to 8 or 9 even if you do land in the target range. However, landing in the target range you will more often than not rise to 8 or 9. I'm trying to lock in a # of minutes to play to keep GS at 9, but as several people have mentioned, every player is different. Besides, managing exact minutes is not easy to do.