Why might a "know it all" witness be avoided during testimony?

A "know it all" witness may be avoided during testimony because they are often difficult to control and may not focus on the relevant questions asked. This type of witness can become sidetracked, providing excessive information or pursuing tangents that do not pertain directly to the case at hand. Their tendency to assert themselves as experts or authorities can lead to lengthy monologues rather than concise, relevant answers, which can frustrate attorneys and unsettle jury members. The main objective during testimony is to present clear and focused information that aids in the understanding of the case, and a witness who does not adhere to this can disrupt the process significantly.