That is a minimum. They will be no less than one hour apart with an hour window for each.
But in your example, you start out in Tomorrowland, need to head over to the opposite side of MK to Frontierland before having to return back to Tomorrowland.
Plus--when is lunch?
If you plan on keeping things that close together, two of the three should be in close vicinity that prevents you from taking huge detours.