Hi guys..I am new to this so excuse my ignorance...

I was wondering about a couple of things regarding Friendly games.:

if you are invited to a friendly by a friend, doesn't affect your players' fatigue, morale and form, and if so, how can you reject it when a friend invites you to a friend and the game played immediately and right there and then? I may not want to play a friendly right before a big match or while I am preparing for a tournament?

Also, could friendlies replace a hard training session or you will still be recommended to have training sessions after a friendly?

Can someone help. Thanks.