International friendlies give team managers the opportunity to experiment with team selection and tactics before the tournament proper, and also allow them to assess the abilities of players they may potentially select for the tournament squad. Players can be booked in international friendlies, and can be suspended from future international matches based on red cards or accumulated yellows in a specified period. Caps and goals scored also count towards a player's career records. 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.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What do friendlies allow managers to experiment with?
team selection and tactics