Well I have a player who averages about 90 minutes a week and still has 9 GS. No GS training ever. I do have a massage doctor, but I think the biggest factor here is his high ST. He always seemed better at keeping his GS at 8 or 9, even though he was playing a lot more than other players. Who still had difficulty keeping their GS at 9 or 8, they do have lower ST though. That's why I think ST has a big difference in keeping GS high.