I'm confused by your post and the rules.
From your post:
As usual, minutes this week only matter for this week.
From the rules:
Players who do not play much each week tend to lose focus and their Game Shape will be sloppy. Players who play too much in a week will get tired and their Game Shape will also be low-quality. These changes are gradual, and will build up over a few weeks' time.
If the rules are correct, then it seems to me that the number of minutes played this week will have some effect on the game shape of our players over the next few weeks.
And if I'm interpreting the rules incorrectly, then I'm not sure why I even scheduled a scrimmage for tonight - I'm training stamina this week, and by playing a scrimmage, I am risking injuries to my players. The only benefit of playing the scrimmage, as far as I can see, is that my players may gain experience from it.
i see it like that, that the actual game shape was affected from the minutes and the gameshape last week. The game shape last week was affected from the minutes last week, and the gs from the week before and so on.
If you play a GS 3 with optimal minutes he will never reach perfect game shape, even when the minutes are perfect. He will raise, but need a few week before he is back in shape.