Hello guys, let me introduce another point of view.
Approach no. 1: Sightseeing/enjoying the day. 1000ls range is enough to scan, whatever you "find". You fly around a system, strain your eyes and have fun doing the "proper exploring".
Time to explore the system: 15m - 1h
Approach no. 2: Speedexploring. You jump into the system, scan, d-scan everything within reasonable range (a.k.a 1000ls) and jump to the next system on your journey. Most of the earth-like worlds are in similar distance the Earth is - 500ls, anyway.
Time to explore the system: 5m
First will give you unforgettable experiences, second will earn you money.

Unless you particularly want to look for distant secondary stars, you don't need advanced scanner at all.