What I got was that there are two types of optimization.
1) rewriting the implementation of a function to be faster or more efficient
2) making it so that function never has to be called in the first place.
What I think OP is trying to say is that we should be trying to do method 2 a lot often when we refactor, but it can be hard to determine why the function was written in the first place simply from the function's existence.
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