You will shoot the scene several times. The entire scene.
For example: Scene 22 is Bob and Mary sitting at a table
- it’s three pages long. You will set up the “Master Shot”
- both people at the table, camera getting a head to foot
shot of both of them. On your slate you will write “Scene
22 - Take 1”
Scene 22 - This will be the entire scene from one angle.
Adjust the lights, move the camera and shoot Bob’s side
of the table.
Scene 22A - Close up of Bob.
Scene 22B - Over Mary’s shoulder on Bob.
Scene 22C - A slow dolly push in on Bob - from a full shot
into a close up.
Scene 22D - an insert shot of Bob lighting a cigarette.
Scene 22E - a close up on Bob’s hand putting the cigarette
in the ash tray.
Scene 22F - a close up of Bob taking the contract, looking
at it and signing it (from Mary’s point of view)
Now move the lights, move the camera and cover the scene
from Bob’s side of the table.
Scene 22G - Close up of Mary.
Scene 22H - Over Bob’s shoulder on Mary.
Scene 22J - A slow dolly push in on Mary - from a full shot
into a close up.
Scene 22K - an insert shot of Mary putting the contract on
the table.
Scene 22L - a close up on Mary’s hand snuffing out the
cigarette in the ash tray.
Scene 22M - a close up shot of Mary putting the contract on
the table, putting a pen on the contract and pushing it to
the middle of the table.
Scene 22P - a close up of Bob taking the contract, looking
at it and signing it (from Bob’s point of view)
And this goes on and on until the entire scene is covered
- until all the shots the director wants have been shot.
Then when you are editing you have plenty of angles to choose
from. All the sound is in sync and if you recorded it well, with no
ambient noise, it will cut together as smoothly as the picture.
And that's the key: record the sound well and you won't have
differences in audio quality. As you already pointed out, you can
use the audio for (for example) scene 22A when cutting to the
reaction shot of scene 22G, or the insert of scene 22M.