As answers are up-voted their place in the list will shift. So assuming that someone reading your answer will be familiar with the content of the one "above" is fraught with danger.
However it seems wasteful to reproduce a slab of someone else's answer when you want to extend it or rebut it (beyond the character length permitted for a comment).
I presume that other SE sites have met and answered this challenge. What advice should new users be given to produce pages that are efficient and effective to read (in a potentially infinite number of arrangements)?