Ok. I understand why one needs a positive foc when using fixed heads, but why wouldn't a neutral foc work well with field tips or mechanicals? I mean, you don't need a heavier nose to provide steerage, nor large helical fletch to stabilize them.

If a bare shaft is the ultimate test of a bow tune job, why wouldn't a neutral foc with a mechanical head and small fletch work? I read in another post that the higher the foc, the sooner an arrow drops off down range, and the lower, the longer it stays on plane.

What am I missing here?