> A depositor might walk in and ask to withdraw more money than the bank has cash on hand.

I'm sure you didn't mean it that way, but that sounds rather like an excuse for a bank to hold on to someone's money. Withdrawals don't have to be in cash, banks can issue cheques or money orders (always assuming they still exist in your jurisdiction!) If not the bank can simply pay out your balance by electronic transfer to an account you specify.

I was referring specifically to those rare cases where someone exercises their right to withdraw coins and Federal Reserve notes despite it being virtually always imprudent. For example here[1] is a story about a man who asked for $600,000 in cash. The bank didn't have that many coins and bills on hand and actually took considerably longer than seven days to acquire it.

[1] https://www.investopedia.com/terms/n/notice-of-withdrawal.as...