I can't answer your question directly because I'm not familiar with the Mahasi method. But I'll say a word on similes.
Similes are excellent at encouraging comprehension of a concept. They literally illustrate it and as they say, a picture tells a thousand words. How much more so does a story of pictures as a good simile provides?
However, similes have their limits. As they are stories, their relevance to reality is always restricted. In the end, reality has to be faced directly without any middleman.
Good luck in your practice.
When this is, that is.
From the arising of this comes the arising of that.
When this isn't, that isn't.
From the cessation of this comes the cessation of that.-SN 12.61Ex nihilo nihil fit.