i'd imagine physical currency is not a problem - it's easy to roll the printers. And there's often a hard limit on how much physical currency can be withdrawn

i'd imagine physical currency is not a problem - it's easy to roll the printers. And there's often a hard limit on how much physical currency can be withdrawn on short notice, and to do more you'd have to make a call to prep the bank first. This means they will have a chance to ship newly minted paper in to cover it, as long as the bank's liquidity allows for it.