In the year and a half I was on SNL, I never saw anybody ad lib anything. For a very good reason - the director cut according to the script. So, if you ad libbed, you'd be off mike and off camera.
-- Harry Shearer
   
Harry Shearer   Name:
Harry Shearer
Type:
Actor
Nationality:
American
Birth:
December 23, 1943
https://www.nutquote.com/quote/Harry_Shearer