Don't change your formation. It's better to keep your formation as it is.
If you change, the players will perform pretty bad and you'll lose the game.
Just keep the morale and condition of your players high, and train when you believe you can afford it.

For example: Your players are around 90% and your game starts in 6 hours. That means you get 10% condition during that time (2 times 5%). If you do nothing, they players will have 99% condition, but if you do some training (like the one with 9%), your players will have 90% condition again when they start the game, but will get lvl up much earlier or already did during that training.

That's what I did 3 Losses 3 draws and 20 wins this season. (although I bought lots of good 5 star players for my team with the tokens I won)