Most audio description gets written after the film is locked — a narrator reading the screen back to a viewer who can't see it. I've come to think that's backwards. If a scene only works because of what it looks like, and you can't say what it looks like in the time the scene gives you, the scene has a problem the edit should have caught.
On In Plain Sight, our accessibility consultant sat in on blocking rehearsals, not just the final color pass. If an action couldn't be described in the natural pause of the dialogue around it, we restaged it. That discipline made the film better for every viewer, not just the ones using the described track.
Three things I now ask on every shoot
Is there a natural pause here for a description to live in. Does this shot tell you something a sighted viewer gets for free. And if I cut this the way I want to, does the meaning survive without the picture.
None of this slows a shoot down much. It mostly just means the accessibility consultant is in the room from day one, not the finishing suite.