Count Pages is about
Analysis (you choice of rule). My main use is size comparison (That is words, not screen fulls). I use the same setting for all books in Calibre. That way I get an idea (that file size alone does not give) of how much reading
this one has compared to
that one
With user allowed font and other changes, counting SCREEN FULLS (?pages) is 90% meaningless.
Please tell me that you are not one of those selfpubers that plays with line spacing and unusual margins to make the work seem bigger than it really is