To test players, if you face a full 1* team you will oversize the skills of your players and you will see who are these who can give you more contribution, these who can be more decisive... then I use these to find ma man for corners and the one to pick freekicks (despite that last seasons I tend more to use the own league games and if one fail continously I change the player for this labour...), then too for boosters, and money.