I fear a higher SF will leave too much free oil on the hair resulting in greasy, heavy hair.
The theory I have learned is that soap washes oil away and doesn't leave oil behind.
If hair is greasy, it wasn't washed well. On the other hand, if hair feels heavy, straw-like, what's left behind is probably soap. ACV will soften that residue (I don't believe it actually washes it away).
Which isn't related directly to the SF, but to the cleaning power the soap has. And is aggravated by an insufficient rinse.
In practice, I have seen that if soap makes a lot of lather, it's a good sign that it will leave little residue.