The checking account I pay my bills from is not connected to the checking account I use my debit card with, and my savings account is at a completely different bank altogether. With all the possibilities for fraud, it's too risky to keep all your money in one place.
I recommend to my employees that they set up a "walking around money" account with it's own debit/ATM card, and just transfer $100-$200 to that account automatically, for just that reason.