Personally, I think Amex is on to something regarding those bonus promotions. I added 4 authorized users for my amex platinum card back in August. I put $500 on each of the four cards in the same day at two CVSs. I was suppose to get 4 x 5000 MR points. But I only got 5000 points after a few days. I did not want to call to alert AMEX about my purchases. But I really doubt the remaining points will ever post.
Back to the topic. I also added 4 spg authorized users around the end of August. And I fulfilled the spending requirements for 4 cards in two days at CVS. So I was hoping to get 10000 SPG in one shot. However, to my surprise, same thing happened again, only 2500 points posted to my account 3 days later. I waited for a few more days till my statement came out. No more bonus points added.