Abrupt shifts in writing should be avoided primarily because they are confusing and can make writing or a conversation difficult to follow. When a piece of writing or dialogue changes direction unexpectedly, it can disrupt the flow and coherence, making it hard for the reader or listener to understand the intended message. This can lead to misunderstandings and frustration, detracting from the overall effectiveness of the communication.
Additionally, avoiding abrupt shifts contributes to creating consistency in voice and tone, which helps maintain the reader's engagement and enhances the clarity of the ideas being expressed. Consistency allows the audience to better anticipate the author's perspective and follow the narrative or argument being presented.