[Brightcolours]

Wait, why do you think some lenses take that wrong final step with PD AF?

I do not think it, I know it. The difference between merely opinion and fact.

 

AF is totally separate from the focus screen, so not going to discuss PD AF algorithms. 

 

Better question: Why do you think the focus screen is linked to the AF system, and why do you think the focus screen should be a different distance for different lenses, while you do not think that about the imaging sensor?