I think that the effects of the minutes played are not linked directly in the week after but it's more a kind of average of the previous weeks; I mean that if you wanna have the best shape for the playoff you've to care about it 2 weeks before the training.
But I agree with you, training GS is a legendary waste of time

1990-2022 Stalinorgel - https://www.youtube.com/watch?v=pV-Xppl6h8Et