I think you just decide on what is a reasonable number of feeds for the night and time to space them apart. Then when they wake up you decide before you go to them if you are going to settle them or if you're going to feed them. If you're going to settle them you just keep going for as long as it takes (you can feed them at the next waking if they go past their 'scheduled' feed time).
Another way of doing it is, some people just settle without feeding at the first waking, whether that is 9pm or 2am, and then take it from there.