Perhaps any pause before interview is to allow those investigating ( be it AAIB or Police) to gather as much factual data from wreckage, maintenance/operating/logbook records, video, eye-witnesses, R/T recordings etc as possible to guide their line of questioning.
If you already know the answers to many questions, it helps you to differentiate between those questions where you are trying to illicit confirmation from the pilot, as distinct from those where you are exploring the things that only he knows: what did he see, think, decide and do in that cockpit on that day.
Edited to add. Alternatively, like many involved in major traumatic incidents, he may have no memory at all of what happened in the period during and immediately leading up to the accident. Totally different environment, but some time ago a motorcyclist ran into the back of my car at speed while I was stationary, waiting to turn right: he was up and walking in the hospital 24 hours later but, to this day, he has no recollection of the accident, or the few minutes leading up to it. No amount of questioning will illicit any useful evidence from him.