i think many people make GS too complicated out out it
1st control ur minutes with sub pattern, not with stamina
2nd the computer coach auto sub out players that are tired during dead ball
3rd studies already showed that avg 40 - 50 minutes is the way to get increase game shape, >80 u likely drop
4th the randomness of GS is likely more than one of the followings comblined
a, pure random factor just for computing distribution among the entire bb population
b, accumulated minutes for 2 or 3 weeks, not just one week
c, a hidden body factor, that encourage/discourage constant GS
d, a form(mind) factor that sum up W/L and stats among a set number of games
e, the role of the player have a positive affect on the minutes too