The Reference Desk/Questions about linking narration in soundtracks

1. Does the linking narration happen every time any character does anything or does it only happen a few times an episode?

2. Can someone provide a quote of a linking narration describing an action-packed scene?

3. Some Doctor Who DVDs include the soundtracks of missing episodes, such as The Crusade (Episodes 2 & 4), Galaxy 4 (Episodes 1, 2 & 4) and The Web Of Fear (Episode 3). Do these soundtracks also have linking narration?