Trigger Top Sear And Cocking Piece Contact Angle

[Edd]

I have done some research about primary extraction and trigger timing on Model 700 actions. One of the details that has been mentioned is, when trimming the contact surface on the cocking piece you need to keep the angle the same as it was. I don't see any reason to be concerned what this angle is as long as the contact point remains at the bottom of the cocking piece. Can someone explain why you need this surface to be at a specific angle?