i once had a classmate who did that. i'm not sure if he was INFP or ISFP, but it drove my prof INSANE. we'd have a roundtable where each of us was expected to share an answer, and of course all the extraverts would usually go first, then the introverts, then finally she would have to call on the last few. and sometimes this one kid would just sit there. and like, not say anything. our prof was a ridiculously tightly wound e1 and WANTED him to share like everyone else and she would just wait impatiently and emote a really high level of aggravation. and eventually either he would say something really brief, or say something of suitable length that was totally appropriate and smart.
it's a curious thing to me, since i typically always have more to say, lol.