Duong Nguyen: This is the first time. I suppose it is a limitation of the question format -- maybe a better discussion format would have been to post comments instead of answers?

My suggestion for this problem would be to post any reply that would result in no further reply as a reply to the parent post (ie after some maximum level, the discussion becomes unthreaded). It jus tfeels like CW is cutting off the conversation if there's no more option to reply.

Richard Zach: Yup that is exactly our reasoning. We didn't want to make the replies infinite as it defeats the purpose of Q&A. But thank you for bringing this up. We have increased the limit from 4 to 7 in the past. We'll think of a better solution on how to properly implement threads in a Q&A format

Duong Nguyen: I think it doesn't happen often to have a lot of comments for an answer. But that is possible when students do not understand the answer properly or there are indeed errors in the answers.

I think it might be better to have a way that somehow automatically guided the replies of answers to the "comments" part instead of showing them in the "answers" part.