For what it's worth, I tried this approach with some success. Starting at a green or blue system (where I could sell data), I scanned the galaxy map and made a note of systems which were just over the 20 LY threshold. Then, I looked at each to see which offered the greatest potential for access to unexplored systems. So, a scanning session will entail me jumping from my Base to the 20+LY point (call it System A). I'll then move along an outward track, scanning as I go & recording systems visited. At a suitable point, I'll plot a route back to Base and head back to sell my data.
Heading back is quicker if you use the "Plot route" button after selecting your base. The brown track will appear, designating your route back, passing through every system. However - if you go into System Map, you can skip certain systems and get back quicker. Just locate a system within your range (with luck it might be 2-3 systems away) & note the name. Then go back to the Navigation list, find the system and select it for jump. Repeat until home. Note - if you do it this way, the brown line remains and makes navigation easier.