Not really, since he's just trying to create a visually pleasing result and can ignore a lot of phenomena that would change the exact course of the river, like

Not really, since he's just trying to create a visually pleasing result and can ignore a lot of phenomena that would change the exact course of the river, like the water speed, water level, erosion resistance of different materials, slope of the terrain... (The example of a circular "river" meandering should be a pretty big hint that it's not physically accurate.)