In many ways would this not only be gratifying to try again and again to defeat a fellow clan member with the friendly member not losing anything from the attack instead of attacking random bases and never knowing if your getting better you would eventually notice your own advancement in trying to beat the same base of a clan member or testing how troops work together without sending you broke and would be a very easy way to help new people understand how the A.I to each unit works
And would also open more opportunities for clans to be more social and active