Surprise! I don't actually "spend on each one." I think the conventional wisdom to spend on your Amex cards doesn’t necessarily mean spend on each one. If you have one or two, yes it probably matters that you spend on each one, especially if your cardmember history with Amex isn’t long. But if you have 5 or 10 Amex cards, it’s probably okay if you spend heavily on a few and have little or no charges in some months on others. I’d say, if we’re not working on MSRs from other issuers, Amex gets more than 3/4 of our spend across various cards — not necessarily evenly, which given the high cost of living around here is substantial.
I don’t have any inside knowledge of Amex’s pop up algorithms, but I think spend is kind of a balancing act. In the first year, I definitely spend on each one, but once I pay an annual fee I ease off a little. I always try to justify keeping an Amex card beyond the first year. If I can get a decent retention offer, that might do it. Ongoing anniversary benefits like FNCs also help justify keeping a card. I haven't spent on my Bonvoy Biz and one of my Bonvoy Amex in a few months, but again I've paid annual fees on them and justify their value with their FNCs. During that time, I’ve been approved for two more Amex cards with no pop up. I put expensive purchases on my Plats for purchase protection and extended warranty. I add Amex Offers that I’ll use to my Plat and Biz Plat so they get some love despite earning only 1x MR, but that’s okay because the Amex Offer gets me a statement credit or MR bonus. Unless it’s like a food Amex Offer that would go so much better on the Gold. Dining and supermarket spend on my Gold for 4x MR. When there are deals on VGC/MCGC at supermarkets, I use my Gold to buy them, then spend the VGC/MCGC elsewhere on otherwise non-bonus spend to pass along the 4x MR earning rate. I spent $30k on my Gold last year doing this, no MS. I did put gas on my BGR for 3x MR. And then I use the BBP for 2x MR on everything else.
So far, no pop up.