Amex afaik encourages prepaying wheras chase is against it, i have had numerous calls with chase regarding an aa and they told me clearly (lending services) that prepaying and paying again is a "internal flag" (as opposed to high spending/limits/debt/hard pulls on your credit report)
They said that you are effectively giving yourself a hight credit line then they gave you.
If ur cl is 5k and u max it out and pay and then charge $500 you end up giving urself a $5500 limit that month.
I did plenty of research on many forums regarding chase aa and almost all cases included prepaying.
From people that I personally know who have been aa'd by chase all of them had high spending together with prepaying (some prepaid and charged more and sone did nit)