I think the "Hillary didn't know how" bit is manufactured for the sole purpose of justifying some of how she did what she did. In other words, her not knowing is probably NOT REALLY TRUE. I thought Hillary was smart? /s
For what it’s worth, I suffered through a 9-hour deposition last year on a civil case with high-dollar NY lawyers. Ms Mills went through days of training in advance of her depo. I was taught to pause 2-3 seconds before answering anything to give my lawyer a chance to object. “I don’t know” is a good answer so long as it’s consistent throughout your testimony. I was under oath, on video, with a transcriber and 4 lawyers in the room.