I leaned towards fishing spots that "looked good", were similar to places I'd caught fish before, were places I'd caught fish before, or were places that fish should be in considering the season & prevailing conditions.

Use of 2d sonar was mostly for depth reading ... as I never really trusted the "fish icons" to actually be showing me real fish, and I was rarely ever moving fast enough to create a "fish arch". Also, I wasn't always (or even usually) fishing below the boat, so what was under me was of less interest than what was visible.

Now, mind you, I was mostly into casting (Bass & Crappie), having transitioned from tying the boat to a tree & tightlining minnows or easing around a stand of trees/stumps and dipping a float/minnow as my primary way of catching Crappie.

Understanding that the 2d cone @ 20deg was only giving me a circle (on the bottom) that was 1/3 as wide as the depth of the water, gave me pause as to how much info was really being shown on the screen. That, in itself, probably influenced my way of using the depthfinder "mostly" to show me the depth of water I was sitting over. Yes, I did use it to find contour changes, some submerged cover, baitfish balls, and the occasional school of fish ... but, primarily it was for knowing the depth of the water, when running on plane or when moving along down the banks, casting to visible cover.

And also understand that I started out with a flasher unit, and my latest/greatest 2d unit was a Eagle Magna II ... up until I bought my most recent boat, which had a Lowrance 2d on the bow & a HB LCR 2d at the console. I sold the Lowrance & replaced it with my current Lowrance DSI, and the HB 2d died last year & will be replaced with a HB 560. I'll still use the HB 2d sonar for depth reading while motoring around, but it will also be used by the back seat partner as their window to the world below them ... while I watch the DI and relay any upcoming info of interest for them to be watching for.

... cp