i read this thread and have seen people allude to the fact that if you "churn" your bank accounts too much, they will suddenly stop allowing you to open more accounts. do we know for sure that's the case? is there anything preventing someone from opening an account for $50k, paying off the credit card, opening another account for $50k, and so on? by my calculations, with one credit card, and a $50k limit, you could earn several hundred thousand miles/month.