When do you encounter analogies most often? analogies are used in research papers. writers often incorporate analogies in poetry. you are often asked to answer analogies in vocabulary and reading tests. you come across analogies in narrative writing.

I think you encounter it most often when: You come across analogies in narrative writing.
Analogies refer to the comparison that a writer made between two things in order to make their explanation became clearer. 
You won't find this in a research paper or reading test because these two are way too formal and you will be less likely to find it in poetry because this type of writing tends to be really abstract.