On your next track day try 2 minutes of toe out.
You will soon realise negative camber does sod all for turn in 
What?
Negative camber does...when you look at the suspension as a whole and look at weight transfer.
As you turn in, and the car transfers more weight onto the loaded wheel, the tyre is flattened into the road, rather than rolling off the tread onto the sidewall.
Turn in is just one part of going through as corner, and turn in feel, corner grip and exit traction are all linked with any one adjustment affecting all three.
If you want to do things properly, then you need a tyre temperature gun and a pad of paper, and you go from there...because just picking a figure like 2 mins toe out is about as scienticic as picking a bit of paper out of a hat.