Most people use it for scanning to find and mark brush piles and laydowns. You need it in the back to do that. The idea is to locate stuff and drop wpts so you can go back and fish them. Side scan helped a friend and I catch 1300 more crappie than normal the first winter we had it.
We drove down banks and recorded them. Then we pulled out in the middle of the lake and played the recordings. As we played them we marked trees and brush that showed up on the screen.