Ground to frame

[Peter_SE]

I´m redoing the electrical system on my KF2 and the previous owner had a wire from batt negative behind the seat to chassie of the plane.

Then the ground bus behind instrument panel was also grounded to the frame.

What is the preffered way?
1. Route a wire from battery negative directly to ground bus
2. Ground the frame

The starter needs separate wire for ground if the frame is not grounded