For me based on a one night game, I think Eric is pretty acurate in his explanation, however that would pertain to just a one night session. For major campaigns I can take up to a month of prep time before I DM the next session.
Don't give a DM too much time to prep - we just have more time to plot out the nasties and villians, for better or worse - LOL
Don't give a DM too much time to prep - we just have more time to plot out the nasties and villians, for better or worse - LOL