I agree with this - the question posed can't possibly be answered. Much of the answers would involve how much one values diamond, the value of ones time, ones personal net worth, etc. To me, I've never got the point of milage running to extend status for a year... if you aren't staying much the value of obtaining diamond isn't really that worth it unless one "collects status." Stay like you normally would and earn the status you normally would unless you're a stay or two away from a large tier change. Diamond challenge when you're only 3/5 trying to get to 12 is a huge hill. I can't possibly see a net win MRing in SCali that many stays for trips involving "AUH, DXB, LHR, and MUC." I guess again it depends on how much you value diamond which at those properties will most likely just be a free breakfast for you and your crew.