Longtime lurker, first time poster - I’m looking at the Amex Platinum Charge card. While it’s sign-up bonus is nice currently (80k), it looks like I missed a 100k sign up bonus points a little while back. Does anyone know how frequently the Amex sign-up bonus change? or have a recent history on the sign up bonus offers for this card? I’m currently weighing up whether to sign-up now or wait a few months to see if the 100k comes back.