The simple answer to your question is -
It depends.
On how rigid your bushings are.
On the proportion of your driving that is street/track
On the basic geometry of the suspension
On how much you value tire wear/life
On how much you value straight-line stability
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Generally for the street you want to -
Maintain zero to a small amount of toe-in under normal driving conditions to increase bump stability and tire life..
For the track you want to -
Have a small to moderate amount of toe-in under cornering conditions with little regard to straight line conditions. This will increase cornering stability and force, and increase roll-understeer.
And that's the way it is.
