every friday 8a.m. U.S. eastern time the training update happens. At that exact moment, the number fo minutes that your players played on the training positions on the 3 last games (last saturday, tuesday and thursday) is summed up and if he played 48 minutes or more on those positions summing those three games, he will get full training. Less minutes, less training.
Then when a new week starts, is the same deal. What happened on the previous week doesn't matter.