I want to know the answer to the following question:
What do friendlies allow managers to experiment with?
All the background I'm provided with is that "In 2004, FIFA ruled that substitutions by a team be limited to six per match in international friendlies, in response to criticism that such matches were becoming increasingly farcical with managers making as many as 11 substitutions per match.". Is that enough to answer the question?
Answer: no