Keep in mind that training only happens one day each week. Friday at 4:00 GI time.
And it's all in at that time. If you change the players training set up 5 minutes before training time happens, his training will affect the new skills the same as if he'd had that set up for the entire week. It doesn't matter if you change or how many times you change. The only thing it considers is what the training is set at during the time of the training update.