I opened 3 credit cards with Amex in 2017, one in 2018, and 2 charge cards in 2017. I canceled one card a week ago and was approved for my 6th credit card in 2 years without the popup. I do spend a good amount of money with Amex though. Usually $2-3k a month even after bonuses are over, so I assume that's why they didn't flag me.