This might be a good place to point out that training only occurs once a week, in an early morning (server time) update on Friday. The game uses whatever coach is present and whatever training is selected at this point.
So, in other words, if you decided to change your training late Thursday night, you would not "lose" anything?
I realize that if you are "getting" the game, you should have a pretty firm idea of what you need/want to train, but,
I can also see the occasional, "WTF was I thinking" moment.