The model underlying training is that you train a particular skill in practice all week, and the players improve by actually utilizing the new skills in games.
But the implementation is that BB doesn't actually check the training setting until Friday. It simply records the minutes played at each position during the week, and then calculates training on Friday based on the setting at that instant.
As a matter of planning, I set the training for the next week after the training update, and then set my lineups accordingly.