That is the way things work most of the time when there are no obstructions. But there are times when there are a couple trees in the wrong place, or maybe just branches. In those situations, it is REALLY handy to have something like the DishformyRV app that uses the phone's camera to project all 3 of the individual western arc satellites as well as all 3 of the eastern arc satellites onto the sky. This allows me to give my golf ball antenna a better starting point.
I have the Winegard X2 which can get either the eastern or western Dish sats. So it can be very helpful to know that the western set is blocked but the eastern is available if I move my X2 20 feet.
This is especially helpful the further north you travel because the sats are lower on the horizon. Sometimes you gotta shoot between trees and then over a ridge.
IMHO that little $5 app is worth 10 times what I paid for it.
Tim