This is one of the most common mistakes I see from students.
An extended metaphor is a single metaphor or analogy used through your entire essay.
Example:
Sometimes an extended metaphor is like a fried egg: you start with your idea, which is like the egg inside its shell, but then you have to crack the egg (or start writing your idea), and then you realize that life is messier than you originally expected (like how the egg is messy) but if you’re patient (like cooking the egg, get it?) you can eventually end up shoehorning this metaphor into your whole essay even though your topic actually has nothing to do with eggs.
You end up with something that looks like this:
Why are these bad?
1. They don't provide any new info or insight about your main topic: YOU!
Think about the example I gave you. Did that egg metaphor really help you understand? Or did it just seem forced?
2. They're intrusive.
You only have a limited number of words (and you're supposed to be talking about yourself)! Don't waste your word count talking about eggs!
3. They make you look like a bad writer.
An extended metaphor is a device that's easy to come up with but almost impossible to pull off. Off the top of my head, I can only think of a handful of writers who have done so successfully (Shakespeare, Elizabeth Bishop, Tim O'Brien, Mary Oliver).
Whatever strategies you choose, you need to make sure that you use them well.
3. They're annoying to read.
Trust me, if you're an AO reading hundreds of essays, you're going to grimace every time you see one of these.
What should I do instead?
Focus on telling a good story that shows off your personality!
– Aaron