That's appropriate in 'right to work' states (which is most of them): you can stand up in a meeting & announce "I quit" (or hear "you're fired"), and that's sufficient notification to end your employment. In other states and countries, usually there is a notification period written into your contract which stipulates how much warning you must give the other party before terminating the contract (rule of thumb is 2 weeks + one week per year of employment).