Anywhere from $1000 to $2000.
My goal is to get a particular debt paid off, review a few stable month's worth of transactions, and then only keep that amount needed in the bank. The rest out.
If you look at the bank runs in Greece & Spain, the new ATM rules there, and some of the prepping our government is doing here for social unrest, it doesn't take a conspiracy nut to be cautious now a days.
Add in winter storms here, power outages, local estate sales / garage sales, and there are practical uses too.
And sorry, I don't buy that the banks can't be closed for more than 3 days! Words and words, let's see what happens on our first bank holiday
And here is my very recent personal experience: I wanted to walk a large amount of cash from my one bank to my other bank down the block to pay off a loan. They didn't have enough.
My wife carries the checkbook, I wanted the transaction to clear immediately - not days later by check. Interest was about $6/day. They wouldn't do ACH type transfer, and were going to charge me $8 for cashier's check. I got mad, told them to "give me my money", and they waived the $8 fee "just this one time".
Since then, for spite & exercise, I walk to my bank every day during lunch and withdraw cash from ATM, pile it up at home, and when YNAB says I'm ready to be even more debt free, I make my cash deposit at bank #2 each month.