I've been asked many times by applicants for the academy, as well as those I help with job interviews; about long vs short answers.
I always ask them if they read novels. I also ask them if they've ever read a technical manual. Could you handle reading a 400 page manual on the complete assembly of a car? That would be pretty dry. Could you handle a 400 page Steven King novel. Probably yes. Definitely much more than the GMC assembly manual.
So, where am I going with this. I have interviewed a lot of people in my life. Some candidates to the academy. Some applying to college. Some job interviews. Some of these people had very interesting stories and lives. I could listen to a 3-5 minute answer from some because they grabbed my attention, kept me interested, and made me want to listen. Then there are some that after 15 seconds, I wish they would just SHUT UP.
So, there is no right answer to your question. Those who interview, sit on boards, etc... are NOT ROBOTS. We are human beings just like you. We are your audience. If you interest us, we will want to listen. Even if it's a longer answer, description, etc... On the other hand, if your attitude sucks, you are dry and not interesting, then even a short answer isn't going to impress us.
But don't take what I say as some guideline. ALL people are interesting to listen to or have a dialog with, IF, they are knowledgeable and passionate about the topic. If the candidate has a passion about serving their country; dropping bombs; willing to die; etc..., and they have a true individual belief and opinion of the topic, then they'll have no problem keeping my attention. Length of the answer won't matter. But if the candidate is trying to give me some "Politically Correct" answer; or one that they think I WANT to hear, or obviously sounds like something their parents or someone else told them to say, or overly rehearsed....... then I probably won't be impressed with it. Long or short.
Just be yourself. Be honest. Be sincere. Make it YOUR ANSWER and not the parent's or someone else's. Then, simply answer the question. Use REAL WORDS. The only time I would recommend using a simply YES/NO type answer, is if it's a question you truly do not care about. But if you don't care about bombing others or dying, then I would have a problem with that. Best of luck.... mike....