During the days of the mint, total float for the month peaked at $450k. Gotta remember back in the day The Zombie Buffalo was allowing the purchase of 30 day CDs by credit card, The First Bank of the Spook wasn't spooked, there were many miles earning debit cards to spend float and turbocharge MS. There were other great opportunities as well. You could have a lot of fun rolling over IRAs (60 day windows) and pushing the funds out checking accounts with miles earning debit cards over and over again.