Very good practice, but tricky with friends. At the very least it's a good idea to just write down all payment time commitments for both parties and explain that it is there to preserve the friendship.That's why I always write a contract before I record anyone, even my friends
What do you mean exactly when you say "performed badly"? Who's performance?The hardest part is getting paid!
I have been forced to discount up to 30% on invoices to one large clients who say they can't pay as product has performed badly.
Mentioning no names (indie label based in London live albums & live DVD's are the main product)