Helicopter requires rover to be near by as means of communications as helicopter itself can not directly communicate. Thus, it originally had a limited time as the rover needs to move on to other activities.
Whenever the rover moves on, the helicopter can move to a new landing spot within range.
If they want to scout each landing site, that requires doing a round-trip one day to get photos and flying out the next day, which limits it to a maximum range of 300m every two days.
The previous rover, Curiosity has driven an average of 8m per day (usually stopping for a few days to to science then driving in bursts of ~30m/day) Ingenuity should be able to keep up.
It would also allow the helicopter to charge directly from the rover, rather than from a clumsy solar panel.