But some people seems so at ease with spontaneity, dealing with dynamic, emergent conversations, and even the ability to direct it to particular directions or narratives. I doubt all of it is preparation.
To the original commenter's point, you don't want to memorize your answers, you just want to explore these conversational avenues and test-drive what you might say, seeing how it sounds, what positions are more defensible, what topics to avoid. This is the skeleton of the conversation you'd like to achieve, the "plan".
Of course no plan survives contact with the enemy. When conversation gets spontaneous / goes off the rails, I try to detach and control my emotions. Sit for a few seconds, consider what you're about to say before speaking, and be straightforward and honest.
That said, the motivation to practice comes from success. If someone tells you you're good at something you'll do it more and be willing to spend more time doing it. Success comes from practice, so the hardest part is getting that first positive feedback if you're starting from a deficit (language barriers, previous criticism). I recommend getting a tutor for just about anything like this. Pay a stranger, whose opinion you don't care about, to get you past the awkward bits and into a range that's better than average.
Also, while some of us come off as comfortable, that doesn't mean we are.
I spend all my time practicing stupid coding questions since I'm prone to screwing up easy ones (I can get em all, just need more time and less pressure).
But I NEVER practice behavioral questions, nor system design. And consistently blow those out of the water. The bar is low in a tech interview, and my personality means that I've had a lot of experience having spontaneous conversation in my life, piecing together coherent narrative on the spot.
1. i like myself regardless of if this other person likes me 2. i will be fine, even if i fuck this up 3. every time im asked is an opportunity to practice, tweak something 4. write what you've been up to down
it's like rapping tbh. you learn snippets and lines that work and then you mix and match them for the context.
you don't want to be deciding word by word but phrase by phrase.
Before he was even London Mayor, so had fewer repeat listeners, a journalist went to three of his speeches in the same year. In each one, Boris arrived and apparently didn’t know where he was. He then made a brilliant speech with the same “ad-lib” jokes, mixed up his reading notes at the same point.
Making public speaking look effortless takes a lot of effort.
I can’t be sure of course, but I would guess that the reasons I get away with very short prep time are:
1. 99% of the time I know the subject inside out, because I wouldn’t be able to do my job if I didn’t, so that is already covered.
2. Sharp focus on prepping exactly the right things - and nothing else. If I’m trying to get a point across, that’s the bit I need to make sure I’ve considered - what the obvious holes are in my argument, how I would answer the obvious questions, etc.
I’m definitely not the smoothest presenter, but I do get great feedback (and am still surprised considering I feel like I’m cheating by not spending hours in prep) so if you are already armed with deep and broad general knowledge in your area, maybe going for the laser focus on the specific points that you really care about and then ‘winging’ the rest might work for you too.
For big presentations, I put in practice time equivalent to 10-20x the time of the talk. For a one hour presentation, I'll practice for 10 hours at least, if not substantially more.
For high-stakes conversations with Important People, I think to myself, in advance: what do I want to achieve from this conversation? What do I need to say or ask in order to achieve those things? This is true even if the conversation is "just a chat." The goal might be as simple as: build credibility and familiarity with Important Person. Pro tip: plan up front what you're going to ask/say if there's awkward silence. It happens even to the best conversationalists. Better to be prepared than to be caught flat footed.
One such preparation happens at school when you prep for debates and speeches. This may not be apparent at that time but I see those who are very coherent in interviews have had some debate prep in their schools or colleges. Just quoting an example. Any public speaking prep actually helps in stitching together multiple ideas as you are talking and as you converse and do it in a coherent way.
I really wish many people had these skills. Most of the meetings I sit in, people take 30 mins to convey what should ideally take like 10 mins. 20 mins is just blabber.
The other counter intuitive prep that personally helped me was GMAT verbal. What started as pure hatred turned into a treasure trove of brevity and coherence. Especially the reading comprehension aspects. A month or two you spend through that exercise really helps in the long run. You get pretty good at communicating your ideas coherently.
The thing is that some of us get practice from just our upbringing and life experiences, others may not have that. So for those others, it's about identifying where they can bolster things and practice.
And as with all human things, natural aptitude varies.
Preparation is all you can control, however.