When you are finished with a program, you should not only ask "does it work?" but also "did I review and edit it propery", "if I want X, how much do I have to change?", and "if I find a mistake in here, where else do I have to fix the same mistake?" etc. Good programming is an organizational task because a program evolves. It is modified to compute more outputs. It is modified to fix bugs. It is modified to consider a broader range of inputs. Unless it is organized properly, these tasks are difficult and costly.
Because a program evolves, a program requires editing---just like a plain old English paper. You must check whether you chose the proper design recipe for each function. You must compare and see whether you have used abstraction properly. If a language offers abstractions, use them. If you see strong similarities, abstract. If you see weak similarities, make a note that one could abstract and why you decided against it.
In short, there is now more flexiblity and, with flexibility, you have more responsibility. Use it well.
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