As someone said earlier, it all depends on your spending patterns and algorithms. Several years ago, had a low six figure domestic purchase sail through (with prior notice). This past October, Mrs. AB was on a tear on Bond Street in London. Our fifth or sixth stop was Smythson for a rather pricey woman's wallet. We went back ten minutes later to get another one for our daughter and Amex held up the charge until they were confident that I had neither lost my mind nor my card. I let them know that Mrs. AB wanted to walk more than 20,000 steps on her FitBit that day and to expect additional charges. No further problems.