Exactly. My checking account earns interest, but right now it's paltry because rates are so low. I have automatic transactions in place to move part of each paycheck into various savings and investment vehicles. I have calibrated it so that the only money left in my checking account is money that is budgeted to be spent that month. In my mind, that is what a checking account is for. In order to maximize the amount of money that's working for me instead of just sitting there, I have shaved it pretty close on the amount of money I leave in my checking account.

All of my regular bills (utilities, insurance, internet, cell phone, etc.) go on my credit card, and they are mostly clustered in the first part of the month. By using my credit card, I don't have to take that money out of my bank account until the end of the month, leaving me free to put money into savings and investment earlier in the month. If I were paying those bills directly out of my checking account, I would have to postpone my savings and investment transfers until later in the month to avoid going negative in my checking account.