Finally, a Corvette will never ever ever be small enough to warrant its evasion as presented in this game. All we have to do is look at strike craft and missiles and the interaction with point defense weapons. If we can take down missiles and strike craft there is nothing a corvette is going to be able to do to evade an attack. It is magnitudes larger and less maneuverable than any missile or strike craft. At the ranges where Corvette weapons are at the travel time for nearly any attack is near instantaneous and your only defense is not being the easiest target.
As Cordone mentioned depends entirely on range, the ability of PD to reliably hit SC and Missiles is just a completely arbitrary game mechanic, it has no basis in reality. Again, Stellaris is not realistic and it's not trying to be.
If we where being realistic kinetics would be pure PD, and lasers would be either the main weapon or PD depending on what type of missle propulsion we where talking about.