gameshape is strongly affected not only by the playing minutes of the previous week, but also the week before.
When you train players (lets say PG/SG trained in jumpshot for example) they will have increased chances to have better gameshape when training refreshes at friday ...BUT playing minutes should be as close to 60 as possible and between 48 to 72 minutes
A quick THEORETICAL example : player A without receiving training and player B receiving training
Week 1 player A has 60 playing minutes , which is the optimum based on years of observation by users
Week 2 player A has 64 minutes, and strong gameshape
Week 3 player A has 58 minutes and proficient gameshape (because in previous 2 weeks he had playing minutes close to 60)
Week 4 player A has 64 proficient gameshape because week 2 and 3 PM were close to 60 again
Week 5 player A has proficient gameshape...
and now player B
Week 1 player B has 85 playing minutes
week 2 player B has 75 playing minutes and respectable gameshape because he played 85 minutes in the previous week
week 3 player B has 64 PM and strong gameshape
week 4 player B 62 PM and still strong gameshape
week 5 player B has proficient gameshape
So you can see that gameshape works like a chain, if you manage your minutes perfectly in the first two weeks, the next weeks are highly affected IMHO
Last season I had a PG that always played 55-65 minutes from the start of the season till the end of it, from week 3 till week 14 he was always proficient with 155000 DMI,with only one week having 120000 or something and strong gameshape which was
I also had my best player an SF playing from 53 to 85 minutes, it was really difficult for me to keep him @ proficient gameshape constantly because his PM fluctuated a lot.
Most of my players have 6 (average) stamina and most of them played close to 60 ( 54 to 68) minutes so most of them were proficient @ gameshape the whole season. I ve seen many users state that stamina also affects gameshape and I have a suspicion (maybe its just me) that a player with 6 stamina needs close to 55-60 minutes to be proficient, a player with 7 stamina needs 60-65 and a player with 8 stamina 65-70, that is just a theory of mine and I cant validate it, it is something I observed through the years