"I hear and I forget. I see and I remember. I do and I understand." ~ Confucius
You can talk me through a kata I'm unfamiliar with all day long, and while you are talking, I can stumble my way through it. But then set me loose to run it completely alone, and I am lost.
You can run a kata I am unfamiliar with so that I can watch you, and I may be able to mimic as a parrot would with words, but it still is not permanently embedded in my mind.
If I'm really going to understand the techniques in the kata, run the kata beside me. Stop me at random points and show me the bunkai for a specific technique. Technique without application is pointless. Explain the why to me, and the how will stick forever.
This is one of the many things I love about our dojo. The why is explained. It's not just punch - kick - block repetition. We are allowed and encouraged to ask for an explanation of the why of any technique.