If I remember correctly, Mark Hamill had his car accident towards the end of filming for Star Wars which is where some of the apparently long shots would have been. All of the long shots would have been for the various reshoots that would have occurred after the end of principal filming. For Empire, the wampa scene was written to try and explain off the facial injuries...and made reasonably successful use of an otherwise traumatic injury.

I do remember reading an article about this somewhere and it was also mentioned in Once Upon A Galaxy as well.