The eastern and western satellites are two separate sets of 3 each satellites. You only need to access one set to get all the Dish channels.
You choose either the eastern OR the western set and then the X2 chooses one of the three satellites within that group, based on the channel you select. It can only focus on one satellite at a time, but will automatically switch between the three as needed, again based on the channel you select.
One of the main benefits of the X2 is that you can access the eastern set of Dish Satellites if the western set is blocked.
Having said all that, there have been times when I could only access 2 satellites from one set. When that happens, you will not have access to all programming.