Post Made Community Wiki by Aniket Inge
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Long methods can be more computationally and space efficient, it can be easier to see the logic and easier to debug them. However these rules only really apply when only one programmer touches that code. The code is going to be a pain to extend if it is not atomic, essentially the next person will have to start from scratch and then debugging and testing this will take for ever as it is not using any known good code.