In the book "Facebook Effect" by David Kirkpatrick[1], one programmer described how Mark Zuckerberg and the other programmers extensively chatted on AOL AIM even though they all sat at the same table elbow-to-elbow.
When one of the new programmers responded to one of MZ's chat texts by just looking up and vocalizing an answer, MZ didn't look away from his laptop to respond. Basically, the new programmer unintentionally broke the silence etiquette. The early Facebook team was using chat as virtual hallway conversations.
It seems the "correct" way to use realtime chat depends on differing personalities?
[1] there was more than one chat story in the book and this was one of them (but don't know for sure if Google Books link will show you the page excerpt): https://books.google.com/books?id=PxTvbM-VCPEC&pg=PA137&lpg=...