perhaps you should be implement to fix a date for friendlys.

the challenger could date a friendly wth 1 or 2 exactly times, send you a request and you can accept or decline.
if you do nothing, no friendly game will be played.

also you cant arrange a friendly immediatly, you have to arrange a game but there has to be 6-10 hours for the game to start with the criterias listed above.

for me this is the best option.

sometime i got my matches in the evening about 18 o'clock, and the next gamethe next day at 9am. in the night a friend arranged a friendly at 2am and the condition of my players gt to 20%, and cant recover till 9 am.

this is the only problem.

just implement that one has to ACCEPT a friendly, not automatically accept it, thats the problem now.