Hi! sorry for the delayed response. I will try and help. It is basically the same in that it is the amp draw pulled from the battery that matters. Whether its supplying power to 1 motor or 4 its still only X amps. with 4 motors you need to add the amp draw of each. Calculating actual flight time can be a bit more complicated as no system pulls exactly the same. Pilots effect this just as much as your components. I do use a tool like -
https://www.ecalc.ch/xcoptercalc.php - as a way to get an estimation.
Hope this helps. If you have any other questions let me know. Looking foward to chatting with you.
Josh