On Literal Interpretation of the Bible, Part 2

Genre Analysis
In “Hermeneutics, Principles and Processes of Biblical Interpretation” by Henry A. Virkler (not to be confused with the Fonz, Henry Winkler) we read the following regarding genre analysis or literary form:
“For purposes of our analysis at this point, it is sufficient to speak of three general literary forms – prose, poetry, and apocalyptic literature.  Apocalyptic writing, found most obviously in the visionary passages of Daniel and Revelation, frequently contains words used symbolically.  Prose and poetry use words in literal and figurative ways: in prose the literal usage predominates; in poetry figured languages is used most often.”
This general division of passages into prose, poetry, and apocalyptic literature would at first seem to solve the predicament outline in my last blog post – On Literal Interpretation of the Bible, Part 1.  The predicament is “how do we determine which passages are literal and which are figurative?”  Virkler gives the following breakdown:
Prose – mostly literal
Poetry – mostly figurative
Apocalyptic – frequently figurative
However, note that in each of these cases there is not a rule for the genre to be all literal or all figurative.  Since each genre has only “mostly” one type the other type cannot be ruled out.  For example, a prose section, although mostly literal, can still have figurative use of language.  Thus, this rule cannot be applied as is to the text.  Additional principles are needed.
Furthermore, the division of “prose, poetry, and apocalyptic” may seem obvious to some, but on what method is each passage to be analyzed to be placed into one of these categories?
Thus, at this point, the method of clarifying which passages in the Bible are literal and which are figurative is not clear to me.  Perhaps this lack of clarity is at root of the major divisions between Christian denominations who are equally unclear about how to interpret Scripture?